LPIC1 Exam Guide
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LPIC1 Exam Guide
Introduction
101.1. Determine and configure hardware settings
101.2. Boot the system
101.3. Change runlevels / boot targets and shutdown or reboot system
102.1. Design hard disk layout
102.2. Install a boot manager
102.3. Manage shared libraries
102.4. Use Debian package management
102.5. Use RPM and YUM package management
103.1. Work on the command line
103.2. Process text streams using filters
103.3. Perform basic file management
103.4. Use streams, pipes and redirects
103.5. Create, monitor and kill processes
103.6. Modify process execution priorities
103.7. Search text files using regular expressions
103.8. Perform basic file editing operations using vi
104.1. Create partitions and filesystems
104.2. Maintain the integrity of filesystems
104.3. Control mounting and unmounting of filesystems
104.4. Manage disk quotas
104.5. Manage file permissions and ownership
104.6. Create and change hard and symbolic links
104.7. Find system files and place files in the correct location
105.1. Customize and use the shell environment
105.2. Customize or write simple scripts
105.3. SQL data management
106.1. Install and configure X11
106.2. Setup a display manager
106.3. Accessibility
107.1. Manage user and group accounts and related system files
107.2. Automate system administration tasks by scheduling jobs
107.3. Localisation and internationalisation
108.1. Maintain system time
108.2. System logging
108.3. Mail Transfer Agent (MTA) basics
108.4. Manage printers and printing
109.1. Fundamentals of internet protocols
109.2. Basic network configuration
109.3. Basic network troubleshooting
109.4. Configure client side DNS
110.1. Perform security administration tasks
110.2. Setup host security
110.3. Securing data with encryption
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102.5. Use RPM and YUM package management

102.5 Use RPM and YUM package management

Weight: 3
Description: Candidates should be able to perform package management using RPM and YUM tools.
Key Knowledge Areas:
    Install, re-install, upgrade and remove packages using RPM and YUM
    Obtain information on RPM packages such as version, status, dependencies, integrity and signatures
    Determine what files a package provides, as well as find which package a specific file comes from
Terms and Utilities:
    rpm
    rpm2cpio
    /etc/yum.conf
    /etc/yum.repos.d/
    yum
    yumdownloader
In this lesson we learn how to work with packages in RedHat Distributions. If you are not familiar with Package and package Manager concepts in linux please study first part of previous lesson.

rpm

RPM (Red Hat Package Manager) is a powerful Package Manager, which can be used to build, install, query, verify, update, and erase individual software packages.
A package consists of an archive of files and meta-data used to install and erase the archive files. The meta-data includes helper scripts, file attributes, and descriptive information about the package.
Packages come in two varieties: binary packages, used to encapsulate software to be installed, and source packages, containing the source code and recipe necessary to produce binary packages. RPM is the only way to install packages under Linux systems, if you’ve installed packages using source code, then rpm won’t manage it.
RPM deals with .rpm files, which contains the actual information about the packages such as: what it is, from where it comes, dependencies info, version info etc.

Where to find RPM packages

list of rpm sites, where we can find and download all RPM packages:
RPM keeps the information of all the installed packages under /var/lib/rpm database.
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[[email protected] ~]# ls -l /var/lib/rpm
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total 86688
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-rw-r--r--. 1 root root 3821568 Dec 5 10:02 Basenames
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-rw-r--r--. 1 root root 16384 Dec 5 10:02 Conflictname
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-rw-r--r-- 1 root root 311296 Dec 8 11:26 __db.001
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-rw-r--r-- 1 root root 90112 Dec 8 11:26 __db.002
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-rw-r--r-- 1 root root 1318912 Dec 8 11:26 __db.003
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-rw-r--r--. 1 root root 1134592 Dec 5 10:02 Dirnames
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-rw-r--r--. 1 root root 32768 Dec 5 10:02 Group
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-rw-r--r--. 1 root root 20480 Dec 5 10:02 Installtid
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-rw-r--r--. 1 root root 69632 Dec 5 10:02 Name
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-rw-r--r--. 1 root root 32768 Dec 5 10:02 Obsoletename
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-rw-r--r--. 1 root root 78909440 Dec 5 10:02 Packages
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-rw-r--r--. 1 root root 2404352 Dec 5 10:02 Providename
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-rw-r--r--. 1 root root 520192 Dec 5 10:02 Requirename
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-rw-r--r--. 1 root root 131072 Dec 5 10:02 Sha1header
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-rw-r--r--. 1 root root 73728 Dec 5 10:02 Sigmd5
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-rw-r--r--. 1 root root 8192 Dec 5 10:02 Triggername
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They are all binary files, try cat Basenames to see.
There are five basic modes for RPM command:
    Install : It is used to install any RPM package.
    Remove : It is used to erase, remove or un-install any RPM package.
    Upgrade : It is used to update the existing RPM package.
    Verify : It is used to verify an RPM packages.
    Query : It is used query any RPM package.

Install an RPM Package

-i is used for installing an rpm software package
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[[email protected] ~]# rpm -ivh zip-3.0-11.el7.x86_64.rpm
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Preparing... ################################# [100%]
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Updating / installing...
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1:zip-3.0-11.el7 ################################# [100%]
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-v verbose for a nicer display ,-h print hash marks as the package archive is unpacked.

Check an Installed RPM Package

-q option query a package:
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[[email protected] ~]# rpm -q zip
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zip-3.0-11.el7.x86_64
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List all files of an installed RPM package

Use -ql (query list) with rpm command:
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[[email protected] ~]# rpm -ql zip
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/usr/bin/zip
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/usr/bin/zipcloak
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/usr/bin/zipnote
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/usr/bin/zipsplit
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/usr/share/doc/zip-3.0
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/usr/share/doc/zip-3.0/CHANGES
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/usr/share/doc/zip-3.0/LICENSE
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/usr/share/doc/zip-3.0/README
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/usr/share/doc/zip-3.0/README.CR
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/usr/share/doc/zip-3.0/TODO
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/usr/share/doc/zip-3.0/WHATSNEW
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/usr/share/doc/zip-3.0/WHERE
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/usr/share/doc/zip-3.0/algorith.txt
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/usr/share/man/man1/zip.1.gz
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/usr/share/man/man1/zipcloak.1.gz
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/usr/share/man/man1/zipnote.1.gz
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/usr/share/man/man1/zipsplit.1.gz
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Query a file that belongs which RPM Package

-qf (query file) option help us to find out which package belongs to a file.
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[[email protected] ~]# rpm -qf /usr/bin/zipsplit
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zip-3.0-11.el7.x86_64
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Query a Information of Installed RPM Package

-qi (query info) option will print the available information of the installed package.
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[[email protected] ~]# rpm -qi zip
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Name : zip
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Version : 3.0
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Release : 11.el7
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Architecture: x86_64
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Install Date: Mon 03 Dec 2018 06:05:54 AM EST
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Group : Applications/Archiving
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Size : 815173
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License : BSD
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Signature : RSA/SHA256, Sun 20 Nov 2016 04:04:58 PM EST, Key ID 24c6a8a7f4a80eb5
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Source RPM : zip-3.0-11.el7.src.rpm
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Build Date : Sat 05 Nov 2016 12:49:55 PM EDT
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Build Host : worker1.bsys.centos.org
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Relocations : (not relocatable)
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Packager : CentOS BuildSystem <http://bugs.centos.org>
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Vendor : CentOS
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URL : http://www.info-zip.org/Zip.html
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Summary : A file compression and packaging utility compatible with PKZIP
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Description :
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The zip program is a compression and file packaging utility. Zip is
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analogous to a combination of the UNIX tar and compress commands and
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is compatible with PKZIP (a compression and file packaging utility for
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MS-DOS systems).
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​
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Install the zip package if you need to compress files using the zip
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program.
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Get the Information of RPM Package Before Installing

-qip (query info package) will print the information of a package , as the package has not been installed there is nothing to read by rpm in its data base, so we need to give full name of the package and it would provide required information directly from rpm package:
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[[email protected] ~]# rpm -qip htop-2.2.0-1.el7.x86_64.rpm
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Name : htop
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Version : 2.2.0
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Release : 1.el7
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Architecture: x86_64
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Install Date: (not installed)
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Group : Unspecified
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Size : 222746
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License : GPLv2+
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Signature : RSA/SHA256, Wed 30 May 2018 06:30:22 PM EDT, Key ID 6a2faea2352c64e5
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Source RPM : htop-2.2.0-1.el7.src.rpm
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Build Date : Wed 30 May 2018 06:26:05 PM EDT
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Build Host : buildvm-31.phx2.fedoraproject.org
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Relocations : (not relocatable)
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Packager : Fedora Project
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Vendor : Fedora Project
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URL : http://hisham.hm/htop/
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Bug URL : https://bugz.fedoraproject.org/htop
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Summary : Interactive process viewer
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Description :
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htop is an interactive text-mode process viewer for Linux, similar to
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top(1).
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-p is used to query information from rpm package. We can omit -p and use Package name instead rpm -qi htop .

check dependencies of RPM Package before Installing

Use -qpR options to do a dependency check before installing or upgrading a package
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[[email protected] ~]# rpm -qpR htop-2.2.0-1.el7.x86_64.rpm
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libc.so.6()(64bit)
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libc.so.6(GLIBC_2.14)(64bit)
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libc.so.6(GLIBC_2.15)(64bit)
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libc.so.6(GLIBC_2.2.5)(64bit)
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libc.so.6(GLIBC_2.3)(64bit)
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libc.so.6(GLIBC_2.3.4)(64bit)
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libc.so.6(GLIBC_2.4)(64bit)
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libc.so.6(GLIBC_2.8)(64bit)
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libgcc_s.so.1()(64bit)
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libgcc_s.so.1(GCC_3.0)(64bit)
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libgcc_s.so.1(GCC_3.3.1)(64bit)
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libm.so.6()(64bit)
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libm.so.6(GLIBC_2.2.5)(64bit)
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libncursesw.so.5()(64bit)
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libtinfo.so.5()(64bit)
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rpmlib(CompressedFileNames) <= 3.0.4-1
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rpmlib(FileDigests) <= 4.6.0-1
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rpmlib(PayloadFilesHavePrefix) <= 4.0-1
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rtld(GNU_HASH)
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rpmlib(PayloadIsXz) <= 5.2-1
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-R List capabilities on which this package depends. we can easily use rpm -qR PackageName to query an installed package.
Query configuration file of Installed RPM Packae
-qc (query configuration file) will query an installed package for its configuration files, if it has any:
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[[email protected] ~]# rpm -qc vsftpd
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/etc/logrotate.d/vsftpd
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/etc/pam.d/vsftpd
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/etc/vsftpd/ftpusers
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/etc/vsftpd/user_list
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/etc/vsftpd/vsftpd.conf
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If the package is not installed use -qpc instead to query a rpm package.

Query documentation of Installed RPM Package

-qdf(query document file) gives a list of available documentation of an installed package:
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[[email protected] ~]# which zip
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/bin/zip
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[[email protected] ~]# rpm -qdf /bin/zip
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/usr/share/doc/zip-3.0/CHANGES
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/usr/share/doc/zip-3.0/LICENSE
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/usr/share/doc/zip-3.0/README
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/usr/share/doc/zip-3.0/README.CR
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/usr/share/doc/zip-3.0/TODO
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/usr/share/doc/zip-3.0/WHATSNEW
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/usr/share/doc/zip-3.0/WHERE
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/usr/share/doc/zip-3.0/algorith.txt
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/usr/share/man/man1/zip.1.gz
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/usr/share/man/man1/zipcloak.1.gz
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/usr/share/man/man1/zipnote.1.gz
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/usr/share/man/man1/zipsplit.1.gz
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Verify a installed Package

-V(verify) verifies a package:
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[[email protected] ~]# rpm -V telnet
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[[email protected] ~]#
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No news is good news.When verifying a package, RPM produces output only if there is a verification failure. When a file fails verification, the format of the output is a bit cryptic, but it packs all the information you need into one line per file. Here is the format: SM5DLUGT c <file> . As an example:
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[[email protected] ~]# rpm -V vsftpd
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S.5....T. c /etc/vsftpd/ftpusers
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Where:
    S is the file size.
    M is the file's mode.
    5 is the MD5 checksum of the file.
    D is the file's major and minor numbers.
    L is the file's symbolic link contents.
    U is owner of the file.
    G is the file's group.
    T is the modification time of the file.
    c appears only if the file is a configuration file. This is handy for quickly identifying config files, as they are very likely to change, and therefore, very unlikely to verify successfully.
    <file> is the file that failed verification. The complete path is listed to make it easy to find.

Verify all RPM Packages

Use -Va(Verify all) to verify all the installed rpm packages.
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[[email protected] ~]# rpm -Va
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S.5....T. c /etc/cgrules.conf
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missing /var/run/pluto
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....L.... c /etc/pam.d/fingerprint-auth
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....L.... c /etc/pam.d/password-auth
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....L.... c /etc/pam.d/postlogin
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....L.... c /etc/pam.d/smartcard-auth
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....L.... c /etc/pam.d/system-auth
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missing /var/run/gluster
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S.5....T. c /etc/yum/pluginconf.d/langpacks.conf
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S.5....T. c /etc/plymouth/plymouthd.conf
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S.5....T. c /etc/cups/cups-browsed.conf
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.M....G.. /var/log/gdm
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missing /var/run/pulse
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S.5....T. c /etc/sysconfig/authconfig
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missing /var/run/wpa_supplicant
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use rpm -Vac to just verify configuration files.There would be some common system script which are routinely changed.

Verify a RPM Package

Verifying a package compares information of installed files of the package against the rpm database.
The-Vp (verify package) is used to verify a package.
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[[email protected] ~]# rpm -Vp zip-3.0-11.el7.x86_64.rpm
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[[email protected] ~]# rpm -Vp htop-2.2.0-1.el7.x86_64.rpm
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missing /usr/bin/htop
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missing /usr/share/applications/htop.desktop
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missing /usr/share/doc/htop-2.2.0
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missing d /usr/share/doc/htop-2.2.0/AUTHORS
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missing d /usr/share/doc/htop-2.2.0/ChangeLog
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missing d /usr/share/doc/htop-2.2.0/README
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missing /usr/share/licenses/htop-2.2.0
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missing l /usr/share/licenses/htop-2.2.0/COPYING
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missing d /usr/share/man/man1/htop.1.gz
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missing /usr/share/pixmaps/htop.png
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List all Installed RPM Packages

-qa (query all) option, will list all the installed rpm packages.
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[[email protected] ~]# rpm -qa
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NetworkManager-team-1.8.0-9.el7.x86_64
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cdparanoia-libs-10.2-17.el7.x86_64
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gtkmm30-3.22.0-1.el7.x86_64
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python-configshell-1.1.fb23-3.el7.noarch
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khmeros-base-fonts-5.0-17.el7.noarch
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liberation-fonts-common-1.07.2-15.el7.noarch
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kexec-tools-2.0.14-17.el7.x86_64
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iptables-1.4.21-18.0.1.el7.centos.x86_64
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gnome-dictionary-libs-3.20.0-1.el7.x86_64
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gd-2.0.35-26.el7.x86_64
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setserial-2.17-33.el7.x86_64
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mozilla-filesystem-1.9-11.el7.x86_64
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...
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<the output has been truncated>
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use --last option to list recently installed RPM Packages.

Upgrade a RPM Package

-U upgrades or installs the package currently installed to a newer version. This is the same as install, except all other version(s) of the package are removed after the new package is installed.
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[[email protected] ~]# rpm -Uvh telnet-0.17-64.el7.x86_64.rpm
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Preparing... ################################# [100%]
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Updating / installing...
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1:telnet-1:0.17-64.el7 ################################# [100%]
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One of the major advantages of using this option is that it will not only upgrade the latest version of any package, but it will also maintain the backup of the older package so that in case if the newer upgraded package does not run the previously installed package can be used again.(via rpm --oldpackage switch or using yum downgrade )
rpm -ivh vs rpm -Uvh
rpm -ivh just installs a package and if the package is already installed it won't do any things, but rpm -Uvh installs it, even if it exists.
Also rpm -ivh might cause having multiple version of a package at the same time but by using rpm -Uvh we are sure that we just have the latest version.
-F will upgrade packages, but only ones for which an earlier version is installed.( means upgrade if installed other wise do noting)

Remove a RPM Package

-e (erase) option is used to remove package (add v or vv for more verbosity):
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[[email protected] ~]# rpm -evv zip
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D: loading keyring from pubkeys in /var/lib/rpm/pubkeys/*.key
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D: couldn't find any keys in /var/lib/rpm/pubkeys/*.key
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D: loading keyring from rpmdb
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D: opening db environment /var/lib/rpm cdb:0x401
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D: opening db index /var/lib/rpm/Packages 0x400 mode=0x0
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D: locked db index /var/lib/rpm/Packages
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D: opening db index /var/lib/rpm/Name 0x400 mode=0x0
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D: read h# 1319 Header SHA1 digest: OK (489efff35e604042709daf46fb78611fe90a75aa)
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D: added key gpg-pubkey-f4a80eb5-53a7ff4b to keyring
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D: read h# 1337 Header SHA1 digest: OK (dd737a402556b7653c2bc971f343532046e26384)
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D: added key gpg-pubkey-352c64e5-52ae6884 to keyring
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D: Using legacy gpg-pubkey(s) from rpmdb
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D: read h# 1341 Header V3 RSA/SHA256 Signature, key ID f4a80eb5: OK
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D: opening db index /var/lib/rpm/Conflictname 0x400 mode=0x0
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D: ========== --- zip-3.0-11.el7 x86_64/linux 0x2
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D: opening db index /var/lib/rpm/Requirename 0x400 mode=0x0
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D: ========== recording tsort relations
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D: ========== tsorting packages (order, #predecessors, #succesors, depth)
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D: 0 0 0 1 -zip-3.0-11.el7.x86_64
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D: erasing packages
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D: Selinux disabled.
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D: closed db index /var/lib/rpm/Conflictname
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D: closed db index /var/lib/rpm/Requirename
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D: closed db index /var/lib/rpm/Name
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D: closed db index /var/lib/rpm/Packages
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D: closed db environment /var/lib/rpm
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D: opening db environment /var/lib/rpm cdb:0x401
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D: opening db index /var/lib/rpm/Packages (none) mode=0x42
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D: sanity checking 1 elements
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D: running pre-transaction scripts
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D: computing 17 file fingerprints
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D: opening db index /var/lib/rpm/Name (none) mode=0x42
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D: opening db index /var/lib/rpm/Basenames (none) mode=0x42
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D: opening db index /var/lib/rpm/Group (none) mode=0x42
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D: opening db index /var/lib/rpm/Requirename (none) mode=0x42
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D: opening db index /var/lib/rpm/Providename (none) mode=0x42
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D: opening db index /var/lib/rpm/Conflictname (none) mode=0x42
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D: opening db index /var/lib/rpm/Obsoletename (none) mode=0x42
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D: opening db index /var/lib/rpm/Triggername (none) mode=0x42
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D: opening db index /var/lib/rpm/Dirnames (none) mode=0x42
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D: opening db index /var/lib/rpm/Installtid (none) mode=0x42
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D: opening db index /var/lib/rpm/Sigmd5 (none) mode=0x42
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D: opening db index /var/lib/rpm/Sha1header (none) mode=0x42
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Preparing packages...
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D: computing file dispositions
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D: 0x0000fd00 4096 10667163 23530388 /
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D: ========== +++ zip-3.0-11.el7 x86_64-linux 0x2
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D: read h# 1341 Header V3 RSA/SHA256 Signature, key ID f4a80eb5: OK
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D: erase: zip-3.0-11.el7 has 17 files
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zip-3.0-11.el7.x86_64
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D: erase 100644 1 ( 0, 0) 619 /usr/share/man/man1/zipsplit.1.gz
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D: erase 100644 1 ( 0, 0) 819 /usr/share/man/man1/zipnote.1.gz
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D: erase 100644 1 ( 0, 0) 951 /usr/share/man/man1/zipcloak.1.gz
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D: erase 100644 1 ( 0, 0) 28496 /usr/share/man/man1/zip.1.gz
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D: erase 100644 1 ( 0, 0) 3395 /usr/share/doc/zip-3.0/algorith.txt
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D: erase 100644 1 ( 0, 0) 13167 /usr/share/doc/zip-3.0/WHERE
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D: erase 100644 1 ( 0, 0) 15731 /usr/share/doc/zip-3.0/WHATSNEW
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D: erase 100644 1 ( 0, 0) 6675 /usr/share/doc/zip-3.0/TODO
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D: erase 100644 1 ( 0, 0) 6430 /usr/share/doc/zip-3.0/README.CR
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D: erase 100644 1 ( 0, 0) 12748 /usr/share/doc/zip-3.0/README
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D: erase 100644 1 ( 0, 0) 3412 /usr/share/doc/zip-3.0/LICENSE
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D: erase 100644 1 ( 0, 0)210354 /usr/share/doc/zip-3.0/CHANGES
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D: erase 040755 2 ( 0, 0) 6 /usr/share/doc/zip-3.0
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D: erase 100755 1 ( 0, 0)100096 /usr/bin/zipsplit
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D: erase 100755 1 ( 0, 0) 95984 /usr/bin/zipnote
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D: erase 100755 1 ( 0, 0)100456 /usr/bin/zipcloak
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D: erase 100755 1 ( 0, 0)215840 /usr/bin/zip
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D: --- h# 1341 zip-3.0-11.el7.x86_64
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D: removing "zip" from Name index.
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D: removing 17 entries from Basenames index.
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D: removing "Applications/Archiving" from Group index.
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D: removing 13 entries from Requirename index.
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D: removing 2 entries from Providename index.
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D: removing 4 entries from Dirnames index.
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D: removing 1 entries from Installtid index.
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D: removing 1 entries from Sigmd5 index.
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D: removing "ccee29b0ebdbefdec09bb543d7ef43882836c1da" from Sha1header index.
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D: running post-transaction scripts
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D: closed db index /var/lib/rpm/Sha1header
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D: closed db index /var/lib/rpm/Sigmd5
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D: closed db index /var/lib/rpm/Installtid
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D: closed db index /var/lib/rpm/Dirnames
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D: closed db index /var/lib/rpm/Triggername
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D: closed db index /var/lib/rpm/Obsoletename
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D: closed db index /var/lib/rpm/Conflictname
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D: closed db index /var/lib/rpm/Providename
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D: closed db index /var/lib/rpm/Requirename
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D: closed db index /var/lib/rpm/Group
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D: closed db index /var/lib/rpm/Basenames
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D: closed db index /var/lib/rpm/Name
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D: closed db index /var/lib/rpm/Packages
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D: closed db environment /var/lib/rpm
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rpm take care of dependencies while removing a package and does not remove package dependencies. on the other hand if a package is required by other pacakage(d) rpm avoid removing that.The –nodeps (Do not check dependencies) option forcefully remove the rpm package from the system. But keep in mind removing particular package may break other working applications.
note:If you've made changes to a configuration file that was originally installed by RPM, your changes won't be lost if you erase the package.
What you can do is just run "rpm -qc packageName" which will show you which configuration files were installed on your system by an rpm. When you have uninstalled the rpm, you can search on your system if any of the files or their backups remain on your system and remove them manually.

rpm2cpio

From time to time, we might find it necessary to extract one or more files from a package file. One way to do this would be to:
    1.
    Install the package
    2.
    Make a copy of the file(s) you need
    3.
    Erase the package
An easier way would be to use rpm2cpio.
What Files Are In a RPM Package?
A rpm package is consist of some of files and directories which has been archived in cpio format, in addition some descriptions and dependencies have been added to that.
What does rpm2cpio do?
As the name implies, rpm2cpio takes an RPM package file and converts it to a cpio archive. next we need to open cpio archive in order to have orginal file structure.
In this case, the cpio options-i Extract one or more files from an archive, -vverboe, list the files processed, and -dCreate leading directories where needed.(We will talk about cpio in next courses)
rpm2cpio takes only only one argument, and even that's optional! The optional argument is the name of the package file to be converted. (If there is no filename specified on the command line, rpm2cpio will simply read from standard input and convert that to a cpio archive.)
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[[email protected] temp]# ls
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zip-3.0-11.el7.x86_64.rpm
3
​
4
[[email protected] temp]# rpm2cpio zip-3.0-11.el7.x86_64.rpm > zip.cpio
5
​
6
[[email protected] temp]# ls
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zip-3.0-11.el7.x86_64.rpm zip.cpio
8
​
9
[[email protected] temp]# cpio -idv < zip.cpio
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./usr/bin/zip
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./usr/bin/zipcloak
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./usr/bin/zipnote
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./usr/bin/zipsplit
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./usr/share/doc/zip-3.0
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./usr/share/doc/zip-3.0/CHANGES
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./usr/share/doc/zip-3.0/LICENSE
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./usr/share/doc/zip-3.0/README
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./usr/share/doc/zip-3.0/README.CR
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./usr/share/doc/zip-3.0/TODO
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./usr/share/doc/zip-3.0/WHATSNEW
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./usr/share/doc/zip-3.0/WHERE
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./usr/share/doc/zip-3.0/algorith.txt
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./usr/share/man/man1/zip.1.gz
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./usr/share/man/man1/zipcloak.1.gz
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./usr/share/man/man1/zipnote.1.gz
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./usr/share/man/man1/zipsplit.1.gz
27
1598 blocks
28
​
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[[email protected] temp]# ls
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usr zip-3.0-11.el7.x86_64.rpm zip.cpio
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[[email protected] temp]# tree usr/
32
usr/
33
├── bin
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│ ├── zip
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│ ├── zipcloak
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│ ├── zipnote
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│ └── zipsplit
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└── share
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├── doc
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│ └── zip-3.0
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│ ├── algorith.txt
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│ ├── CHANGES
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│ ├── LICENSE
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│ ├── README
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│ ├── README.CR
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│ ├── TODO
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│ ├── WHATSNEW
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│ └── WHERE
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└── man
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└── man1
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├── zip.1.gz
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├── zipcloak.1.gz
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├── zipnote.1.gz
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└── zipsplit.1.gz
55
​
56
6 directories, 16 files
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While there's nothing wrong with using rpm2cpio to actually create a cpio archive file, it's takes a few more steps and uses a bit more disk space than is strictly necessary. A somewhat cleaner approach would be to pipe rpm2cpio's output directly into cpio:
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[[email protected] temp]# rm -rf usr/
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​
3
[[email protected] temp]# ls
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zip-3.0-11.el7.x86_64.rpm zip.cpio
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​
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[[email protected] temp]# rpm2cpio zip-3.0-11.el7.x86_64.rpm | cpio -t
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./usr/bin/zip
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./usr/bin/zipcloak
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./usr/bin/zipnote
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./usr/bin/zipsplit
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./usr/share/doc/zip-3.0
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./usr/share/doc/zip-3.0/CHANGES
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./usr/share/doc/zip-3.0/LICENSE
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./usr/share/doc/zip-3.0/README
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./usr/share/doc/zip-3.0/README.CR
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./usr/share/doc/zip-3.0/TODO
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./usr/share/doc/zip-3.0/WHATSNEW
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./usr/share/doc/zip-3.0/WHERE
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./usr/share/doc/zip-3.0/algorith.txt
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./usr/share/man/man1/zip.1.gz
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./usr/share/man/man1/zipcloak.1.gz
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./usr/share/man/man1/zipnote.1.gz
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./usr/share/man/man1/zipsplit.1.gz
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1598 blocks
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[[email protected] temp]# ls
26
zip-3.0-11.el7.x86_64.rpm zip.cpio
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we used the-t option to direct cpio to produce a "table of contents" of the archive created by rpm2cpio. This can make it much easier to get the right filename and path when you want to extract a file. An easier way to exctract would be rpm2cpio package.rpm | cpio id .
Warning! Becarefull when removing extracted package (usr vs /usr)

YUM

The YUM (Yellowdog Updater Modified) is an open-source command-line package-management utility for Linux operating systems using the RPM Package Manager. Yum allows automatic updates, package and dependency management, on RPM-based distributions.
As a high-level tool,like the Advanced Packaging Tool (APT) from Debian, yum works with software repositories (collections of packages), which can be accessed locally or over a network connection.
Yum is implemented as libraries in the Python programming language, with a small set of programs that provide a command-line interface. GUI-based wrappers such as yumex also exist.

/etc/yum.conf

The configuration file for yum and related utilities is located at /etc/yum.conf.
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[[email protected] ~]# cat /etc/yum.conf
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[main]
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cachedir=/var/cache/yum/$basearch/$releasever
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keepcache=0
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debuglevel=2
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logfile=/var/log/yum.log
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exactarch=1
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obsoletes=1
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gpgcheck=1
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plugins=1
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installonly_limit=5
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bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum
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distroverpkg=centos-release
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​
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​
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# This is the default, if you make this bigger yum won't see if the metadata
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# is newer on the remote and so you'll "gain" the bandwidth of not having to
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# download the new metadata and "pay" for it by yum not having correct
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# information.
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# It is esp. important, to have correct metadata, for distributions like
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# Fedora which don't keep old packages around. If you don't like this checking
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# interupting your command line usage, it's much better to have something
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# manually check the metadata once an hour (yum-updatesd will do this).
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# metadata_expire=90m
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​
26
# PUT YOUR REPOS HERE OR IN separate files named file.repo
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# in /etc/yum.repos.d
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This file contains one mandatory [main] section, which allows us to set Yum options that have global effect, and can also contain one or more [repository] sections, which allow us to set repository-specific options. However, it is recommended to define individual repositories in new or existing .repo files in the /etc/yum.repos.d/ directory.

/etc/yum.repos.d

YUM Repository configuration files are stored in /etc/yum.repos.d directory. It contains several .repo files.
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[[email protected] ~]# ls /etc/yum.repos.d/
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CentOS-Base.repo CentOS-fasttrack.repo CentOS-Vault.repo
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CentOS-CR.repo CentOS-Media.repo epel.repo
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CentOS-Debuginfo.repo CentOS-Sources.repo epel-testing.repo
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Lets take a look at CentOS-Base.repo file:
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[[email protected] ~]# cat /etc/yum.repos.d/CentOS-Base.repo
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# CentOS-Base.repo
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#
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# The mirror system uses the connecting IP address of the client and the
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# update status of each mirror to pick mirrors that are updated to and
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# geographically close to the client. You should use this for CentOS updates
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# unless you are manually picking other mirrors.
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#
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# If the mirrorlist= does not work for you, as a fall back you can try the
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# remarked out baseurl= line instead.
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#
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#
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​
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[base]
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name=CentOS-$releasever - Base
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mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
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#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
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gpgcheck=1
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gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
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​
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#released updates
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[updates]
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name=CentOS-$releasever - Updates
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mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
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#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
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gpgcheck=1
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gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
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​
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#additional packages that may be useful
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[extras]
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name=CentOS-$releasever - Extras
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mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
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#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
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gpgcheck=1
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gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
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​
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#additional packages that extend functionality of existing packages
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[centosplus]
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name=CentOS-$releasever - Plus
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mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
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#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
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gpgcheck=1
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enabled=0
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gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
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Repository configuration files tell yum information about the actual repository (where package files are physically located). While there are a number of optional elements, each .repo file is required to have:
    Repository ID - A one word unique repository ID e.g. [localrepo].
    Name - A human readable name for the repository e.g. name=Awesome Local Repo
    MirrorList : A mirror list is a list of URLs where Package repositories are stored/present.
    Baseurl - A URL to the repodata directory (where the actual files are kept). file://path, ftp://link, http://link, and https://link addresses are all valid options.
    Enabled - Whether or not to enable the repository for use when performing updates and installs e.g. enabled=1 (1 means "use this repository", 0 defines "do not use this repository").
    Gpgcheck - Enable/disable GPG signature checking (example: gpgcheck=1)
    Gpgkey - URL to the GPG key (example: gpgkey=http://mirror.cisp.com/CentOS/6/os/i386/RPM-GPG-KEY-CentOS-6\​
GPG is a digital signature check , which is used to verify the package is modified in between your downloads or after making the package, It help to verify the that you are installing the correct package with out any modification from 3 party or a hacker.
YUM can use numerous third party repositories to install packages automatically by resolving their dependencies issues.

List Enabled Yum Repositories

yum repolist list all enabled Yum repositories in your system:
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[[email protected] ~]# yum repolist
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Loaded plugins: fastestmirror, langpacks
3
Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: mirror.karneval.cz
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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repo id repo name status
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base/7/x86_64 CentOS-7 - Base 9,911
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epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64 12,725
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extras/7/x86_64 CentOS-7 - Extras 434
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updates/7/x86_64 CentOS-7 - Updates 1,614
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repolist: 24,684
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To list all Enabled and Disabled Yum Repositories use yum repolist all command.

Install a Package with YUM

We can install new software on Red Hat/CentOS Linux with yum install packagename command from console.
Running this command first checks for existing YUM Repository configuration files in /etc/yum.repos.d/ directory. It reads each YUM Repository configuration file to get the information required to download and install new software, resolves software dependencies and installs the required RPM package files.
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[[email protected] ~]# yum install zip
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Loaded plugins: fastestmirror, langpacks
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Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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Resolving Dependencies
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--> Running transaction check
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---> Package zip.x86_64 0:3.0-11.el7 will be installed
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--> Finished Dependency Resolution
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​
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Dependencies Resolved
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​
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=======================================================================================
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Package Arch Version Repository Size
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=======================================================================================
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Installing:
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zip x86_64 3.0-11.el7 base 260 k
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​
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Transaction Summary
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=======================================================================================
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Install 1 Package
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​
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Total download size: 260 k
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Installed size: 796 k
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Is this ok [y/d/N]: y
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Downloading packages:
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zip-3.0-11.el7.x86_64.rpm | 260 kB 00:00:46
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Running transaction check
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Running transaction test
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Transaction test succeeded
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Running transaction
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Installing : zip-3.0-11.el7.x86_64 1/1
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Verifying : zip-3.0-11.el7.x86_64 1/1
36
​
37
Installed:
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zip.x86_64 0:3.0-11.el7
39
​
40
Complete!
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use -y option if you do not like to be asked for confimation. If you have a rpm package use yum localinstall abc.rpm .

Removing a Package with YUM

yum remove packagename remove a package completely with their all dependencies.
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[[email protected] ~]# yum remove zip
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Loaded plugins: fastestmirror, langpacks
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Resolving Dependencies
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--> Running transaction check
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---> Package zip.x86_64 0:3.0-11.el7 will be erased
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--> Finished Dependency Resolution
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​
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Dependencies Resolved
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​
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=======================================================================================
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Package Arch Version Repository Size
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=======================================================================================
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Removing:
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zip x86_64 3.0-11.el7 @base 796 k
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​
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Transaction Summary
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=======================================================================================
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Remove 1 Package
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​
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Installed size: 796 k
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Is this ok [y/N]: y
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Downloading packages:
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Running transaction check
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Running transaction test
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Transaction test succeeded
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Running transaction
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Erasing : zip-3.0-11.el7.x86_64 1/1
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Verifying : zip-3.0-11.el7.x86_64 1/1
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​
30
Removed:
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zip.x86_64 0:3.0-11.el7
32
​
33
Complete!
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Same way the remove command will ask confirmation before removing a package. To disable it just add option -y .

Search for a Package using YUM

Use yum search function to search all the available packages to match the name of the package you specified.
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[[email protected] ~]# yum search firefox
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Loaded plugins: fastestmirror, langpacks
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Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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================================ N/S matched: firefox =================================
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firefox.x86_64 : Mozilla Firefox Web browser
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firefox.i686 : Mozilla Firefox Web browser
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firefox-noscript.noarch : JavaScript white list extension for Mozilla Firefox
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firefox-pkcs11-loader.x86_64 : Helper script for Firefox that sets up the browser for
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: authentication with Estonian ID-card
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mozilla-adblockplus.noarch : Adblocking extension for Mozilla Firefox, Thunderbird, and
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: SeaMonkey
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mozilla-https-everywhere.noarch : HTTPS enforcement extension for Mozilla Firefox
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mozilla-noscript.noarch : JavaScript white list extension for Mozilla Firefox
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mozilla-requestpolicy.noarch : Firefox and Seamonkey extension that gives you control
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: over cross-site requests
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mozilla-ublock-origin.noarch : An efficient blocker for Firefox
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webextension-token-signing.x86_64 : Firefox extension for signing with your eID on the
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: web
23
​
24
Name and summary matches only, use "search all" for everything.
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Get Information of a Package using YUM

Withyum info packagename we can get information of a package before installing or an installed package:
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[[email protected] ~]# htop
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bash: htop: command not found...
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Similar command is: 'top'
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[[email protected] ~]# yum info htop
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Loaded plugins: fastestmirror, langpacks
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Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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Available Packages
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Name : htop
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Arch : x86_64
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Version : 2.2.0
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Release : 1.el7
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Size : 103 k
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Repo : epel/x86_64
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Summary : Interactive process viewer
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URL : http://hisham.hm/htop/
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License : GPLv2+
21
Description : htop is an interactive text-mode process viewer for Linux, similar to
22
: top(1).
Copied!

Get information about dependencies of a package

Use yum deplist command to know about dependencies of a package which would be installed on our system:
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[[email protected] ~]# yum deplist htop
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Loaded plugins: fastestmirror, langpacks
3
Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: mirror.23media.de
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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package: htop.x86_64 2.2.0-1.el7
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dependency: libc.so.6(GLIBC_2.15)(64bit)
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provider: glibc.x86_64 2.17-222.el7
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dependency: libgcc_s.so.1()(64bit)
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provider: libgcc.x86_64 4.8.5-28.el7_5.1
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dependency: libgcc_s.so.1(GCC_3.0)(64bit)
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provider: libgcc.x86_64 4.8.5-28.el7_5.1
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dependency: libgcc_s.so.1(GCC_3.3.1)(64bit)
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provider: libgcc.x86_64 4.8.5-28.el7_5.1
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dependency: libm.so.6()(64bit)
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provider: glibc.x86_64 2.17-222.el7
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dependency: libm.so.6(GLIBC_2.2.5)(64bit)
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provider: glibc.x86_64 2.17-222.el7
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dependency: libncursesw.so.5()(64bit)
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provider: ncurses-libs.x86_64 5.9-14.20130511.el7_4
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dependency: libtinfo.so.5()(64bit)
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provider: ncurses-libs.x86_64 5.9-14.20130511.el7_4
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dependency: rtld(GNU_HASH)
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provider: glibc.x86_64 2.17-222.el7
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provider: glibc.i686 2.17-222.el7
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yum installautomatically installs all of them.

Yum Provides Function

yum provide finds packages that provide the queried file:
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[[email protected] ~]# yum provides /etc/updatedb.conf
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Loaded plugins: fastestmirror, langpacks
3
Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.besthosting.ua
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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mlocate-0.26-8.el7.x86_64 : An utility for finding files by name
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Repo : base
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Matched from:
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Filename : /etc/updatedb.conf
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​
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​
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​
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mlocate-0.26-6.el7.x86_64 : An utility for finding files by name
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Repo : @anaconda
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Matched from:
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Filename : /etc/updatedb.conf
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also we can useyum whatprovide /*filename instead.

List all Available Packages

yum list list all the available packages in the Yum database.
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[[email protected] ~]# yum list
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List all Installed Packages using YUM

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[[email protected] ~]# yum list installed
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Working with yum Cache

By default, yum deletes downloaded data files when they are no longer needed after a successful operation. This minimizes the amount of storage space that yum uses. However, we can enable caching, so that the package files downloaded by yum stay in cache directories. By using cached data, you can carry out certain operations without a network connection, we can also copy packages stored in the caches and reuse them elsewhere.
Yum stores temporary files in the/var/cache/yum/$basearch/$releasever/directory,
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[[email protected] ~]# ls /var/cache/yum/x86_64/7/
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base epel extras timedhosts timedhosts.txt updates
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Each configured repository has one subdirectory.T o change the default cache location, modify the cachedir option in the [main] section of the /etc/yum.confconfiguration file.
Enabling the cache
To retain the cache of packages after a successful installation, we can enable the cache editing keppcache = 1 in the [main] section of/etc/yum.conf.
To download and make usable all the metadata for the currently enabled yum repositories, use yum makecache command.It makes sure that the cache is fully up to date with all metadata.This make sure that the cache is fully up to date with all metadata. To set the time after which the metadata will expire, use the metadata-expire setting in/etc/yum.conf.
Using yum in Cache-only Mode
To carry out a yum command without a network connection, add the -C (not -c )or --cacheonly command-line option. With this option, yum proceeds without checking any network repositories, and uses only cached files. In this mode, yum may only install packages that have been downloaded and cached by a previous operation.
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[[email protected] ~]# yum -C install zip
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Loaded plugins: fastestmirror, langpacks
3
Resolving Dependencies
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--> Running transaction check
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---> Package zip.x86_64 0:3.0-11.el7 will be installed
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--> Finished Dependency Resolution
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​
8
Dependencies Resolved
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​
10
=======================================================================================
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Package Arch Version Repository Size
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=======================================================================================
13
Installing:
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zip x86_64 3.0-11.el7 base 260 k
15
​
16
Transaction Summary
17
=======================================================================================
18
Install 1 Package
19
​
20
Total download size: 260 k
21
Installed size: 796 k
22
Is this ok [y/d/N]:
Copied!
clearing the yum caches
It is often useful to remove entries accumulated in the /var/cache/yum/ directory. If we remove a package from the cache, we do not affect the copy of the software installed on our system. To remove all entries for currently enabled repositories from the cache, run yum clean all as a root.

Check for Available Updates using Yum

use yum check-update To find how many of installed packages on our system have updates available:
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[[email protected] ~]# yum check-update
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Loaded plugins: fastestmirror, langpacks
3
Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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​
9
ModemManager.x86_64 1.6.10-1.el7 base
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ModemManager-glib.x86_64 1.6.10-1.el7 base
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NetworkManager.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-adsl.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-bluetooth.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-glib.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-libnm.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-ppp.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-team.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-tui.x86_64 1:1.10.2-16.el7_5 updates
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NetworkManager-wifi.x86_64 1:1.10.2-16.el7_5 updates
20
...
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<output has been truncated>
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Update System using Yum

yum update keep our system up-to-date with all security and binary package updates
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[[email protected] ~]# yum update
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Loaded plugins: fastestmirror, langpacks
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Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
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* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
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Resolving Dependencies
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--> Running transaction check
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---> Package ModemManager.x86_64 0:1.6.0-2.el7 will be updated
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---> Package ModemManager.x86_64 0:1.6.10-1.el7 will be an update
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...
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--> Finished Dependency Resolution
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​
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Dependencies Resolved
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​
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=======================================================================================
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Package Arch Version Repository
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Size
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=======================================================================================
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Installing:
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grub2 x86_64 1:2.02-0.65.el7.centos.2 base 29 k
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replacing grub2.x86_64 1:2.02-0.64.el7.centos
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grub2-tools x86_64 1:2.02-0.65.el7.centos.2 base 1.8 M
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replacing grub2-tools.x86_64 1:2.02-0.64.el7.centos
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grub2-tools-extra x86_64 1:2.02-0.65.el7.centos.2 base 993 k
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replacing grub2-tools.x86_64 1:2.02-0.64.el7.centos
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grub2-tools-minimal x86_64 1:2.02-0.65.el7.centos.2 base 170 k
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replacing grub2-tools.x86_64 1:2.02-0.64.el7.centos
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kernel x86_64 3.10.0-862.14.4.el7 updates 46 M
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Updating:
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ModemManager x86_64 1.6.10-1.el7 base 735 k
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ModemManager-glib x86_64 1.6.10-1.el7 base 231 k
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NetworkManager x86_64 1:1.10.2-16.el7_5 updates 1.7 M
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NetworkManager-adsl x86_64 1:1.10.2-16.el7_5 updates 159 k
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NetworkManager-bluetooth x86_64 1:1.10.2-16.el7_5 updates 179 k
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...
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mesa-libwayland-egl x86_64 17.2.3-8.20171019.el7 base 17 k
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unbound-libs x86_64 1.6.6-1.el7 base 405 k
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volume_key-libs x86_64 0.3.9-8.el7 base 140 k
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​
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Transaction Summary
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=======================================================================================
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Install 5 Packages (+20 Dependent packages)
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Upgrade 578 Packages
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​
47
Total size: 552 M
48
Is this ok [y/d/N]: y
49
...
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Updating a Package using YUM

yum update packagenamewill update a package and automatically resolves all dependencies issues and install them.
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[[email protected] ~]# yum update firefox -y
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Loaded plugins: fastestmirror, langpacks
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Loading mirror speeds from cached hostfile
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* base: bay.uchicago.edu
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* epel: epel.mirror.far.fi
6
* extras: mirror.atlanticmetro.net
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* updates: mirror.atlanticmetro.net
8
Resolving Dependencies
9
--> Running transaction check
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---> Package firefox.x86_64 0:52.2.0-2.el7.centos will be updated
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---> Package firefox.x86_64 0:60.3.0-1.el7.centos will be an update
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--> Processing Dependency: nss >= 3.36.0 for package: firefox-60.3.0-1.el7.centos.x86_64
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--> Processing Dependency: nspr >= 4.19.0 for package: firefox-60.3.0-1.el7.centos.x86_64
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--> Processing Dependency: libdbus-1.so.3(LIBDBUS_1_3)(64bit) for package: firefox-60.3.0-1.el7.centos.x86_64
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...
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Dependencies Resolved
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=======================================================================================
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Package Arch Version Repository Size
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=======================================================================================
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Updating:
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firefox x86_64 60.3.0-1.el7.centos updates 91 M
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Updating for dependencies:
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dbus x86_64 1:1.10.24-7.el7 base 245 k
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dbus-libs x86_64 1:1.10.24-7.el7 base 169 k
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dbus-x11 x86_64 1:1.10.24-7.el7 base 47 k
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...
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Transaction Summary
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=======================================================================================
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Upgrade 1 Package (+10 Dependent packages)
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​
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Total size: 93 M
32
Downloading packages:
33
Running transaction check
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Running transaction test
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Transaction test succeeded
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Running transaction
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Updating : nspr-4.19.0-1.el7_5.x86_64 1/22
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Updating : nss-util-3.36.0-1.el7_5.x86_64 2/22
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...
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Cleanup : 1:dbus-libs-1.6.12-17.el7.x86_64 20/22
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Cleanup : nspr-4.13.1-1.0.el7_3.x86_64 21/22
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Cleanup : nss-softokn-freebl-3.28.3-6.el7.x86_64 22/22
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Verifying : 1:dbus-x11-1.10.24-7.el7.x86_64 1/22
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Verifying : 1:dbus-libs-1.10.24-7.el7.x86_64 2/22
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Verifying : firefox-60.3.0-1.el7.centos.x86_64 3/22
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...
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Verifying : firefox-52.2.0-2.el7.centos.x86_64 21/22
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Verifying : nss-softokn-freebl-3.28.3-6.el7.x86_64 22/22
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​
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Updated:
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firefox.x86_64 0:60.3.0-1.el7.centos
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​
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Dependency Updated:
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dbus.x86_64 1:1.10.24-7.el7 dbus-libs.x86_64 1:1.10.24-7.el7
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dbus-x11.x86_64 1:1.10.24-7.el7 nspr.x86_64 0:4.19.0-1.el7_5
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nss.x86_64 0:3.36.0-7.el7_5 nss-softokn.x86_64 0:3.36.0-5.el7_5
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nss-softokn-freebl.x86_64 0:3.36.0-5.el7_5 nss-sysinit.x86_64 0:3.36.0-7.el7_5
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nss-tools.x86_64 0:3.36.0-7.el7_5 nss-util.x86_64 0:3.36.0-1.el7_5
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​
60
Complete!
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If you have a rpm package you can use yum localupdate abc.rpm .

YUM update vs YUM upgrade

yum upgrade and yum update will perform the same function that update to the latest current version of package.
yum upgrade forces the removal of obsolete packages, while yum update may or may not also do this. The removal of obsolete packages can be risky, as it may remove packages that you use. This makes yum update the safer option.
note: The behaviour might be different based on your distribution and version.

Working with Group Packages

In Linux, number of packages are bundled to particular group , called Group Packages. Instead of working with individual packages with yum, we can work particular group that will install/remove/update all the related packages that belongs to the group.
1
# yum grouplist :
2
# yum groupinstall 'MySQL Database'
3
# yum groupupdate 'DNS Name Server'
4
# yum groupremove 'DNS Name Server'
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YUM Shell

Yum utility provides a custom shell where you can execute multiple commands.
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[[email protected] ~]# yum shell
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Loaded plugins: fastestmirror, langpacks
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> list
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list list-sec list-security list-updateinfo
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> group
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group groupinfo grouplist groups
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grouperase groupinstall groupremove groupupdate
8
> quit
9
Leaving Shell
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yumdownloader

How do I use yum to download a package without installing it? There are multiple ways in which you can download a yum package without installing it. The 2 most commonly used methods are described here in the post.
    1.
    using the “downloadonly” plugin for yum
    2.
    using “yumdownloader” utility.
Method 1 : using the “downloadonly” plugin for yum:
First install the package including “downloadonly” plugin:
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(RHEL5)
2
# yum install yum-downloadonly
3
​
4
(RHEL6)
5
# yum install yum-plugin-downloadonly
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syntax:
1
yum install --downloadonly --downloaddir=[directory] [package]
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If you do not use --downloaddir option, it would be saved in /var/cache/yum/ in rhel-{arch}-channel/packages directory.
example:
1
yum install --downloadonly --downloaddir=/tmp firefox
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Method 2 : using the “yumdownloader” utility
First install the yum-utils package:
1
yum install yum-utils
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syntax:
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yumdownloader --destdir [directory] [package]
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example:
1
yumdownloader --destdir /tmp firefox
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tryyumdownloader --help to see some of usefull switches such as :
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--urls Instead of downloading RPMs, list the URLs that would be downloaded.
2
--resolve When downloading RPMs, resolve dependencies and also download the required packages.
3
--source Instead of downloading the binary RPMs, download the source RPMs
4
...
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the --resolve switch is usefull inorder to download a package ant its dependencies and lets us to use them in other system.

to view history of Yum commands (update, install, remove)

We can either use yum history command :
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[[email protected] ~]# yum history
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Loaded plugins: fastestmirror, langpacks
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ID | Login user | Date and time | Action(s) | Altered
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-------------------------------------------------------------------------------
5
11 | payam <payam> | 2018-12-05 10:02 | Update | 11
6
10 | payam <payam> | 2018-12-04 14:54 | Erase | 1
7
9 | payam <payam> | 2018-12-04 14:45 | Install | 1
8
8 | payam <payam> | 2018-12-04 14:44 | Erase | 1 <
9
7 | payam <payam> | 2018-12-03 06:03 | Erase | 3 >
10
6 | payam <payam> | 2018-11-19 05:14 | I, U | 3
11
5 | payam <payam> | 2018-11-18 03:46 | Install | 1
12
4 | payam <payam> | 2018-10-20 13:01 | Install | 1
13
3 | payam <payam> | 2018-10-13 03:38 | Install | 12
14
2 | payam <payam> | 2018-08-26 04:48 | I, U | 3
15
1 | System <unset> | 2017-10-28 11:18 | Install | 1318
16
history list
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or see yum log file in /var/log/yum directory:
1
[[email protected] ~]# tail -5 /var/log/yum.log
2
Dec 05 10:02:27 Updated: nss-sysinit-3.36.0-7.el7_5.x86_64
3
Dec 05 10:02:27 Updated: nss-3.36.0-7.el7_5.x86_64
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Dec 05 10:02:37 Updated: firefox-60.3.0-1.el7.centos.x86_64
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Dec 05 10:02:37 Updated: nss-tools-3.36.0-7.el7_5.x86_64
6
Dec 05 10:02:37 Updated: 1:dbus-x11-1.10.24-7.el7.x86_64
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Summary

Fedora Family System:
    Red Hat Package Manager (rpm):
      low-level or underlying packet manager
    Yellowdog Updater (yum):
      The high-level package manager differs between distribution but yum is commonly used
    Dandified Yum (dnf):
      It is the next-generation version of yum
.
.
.
sources:
​http://www.pepedocs.com/notes?tid=linux&nid=lfs101x#ch6​
​https://linux.die.net/man/8/rpm​
​https://www.tecmint.com/20-practical-examples-of-rpm-commands-in-linux/​
​http://ftp.rpm.org/max-rpm/s1-rpm-verify-output.html(rpm -V)
​https://serverfault.com/questions/747089/whats-the-diff-between-rpm-u-and-rpm-f?rq=1​
​http://ftp.rpm.org/max-rpm/s1-rpm-erase-and-config-files.html​
​https://www.linuxquestions.org/questions/linux-software-2/can-rpm-remove-config-files-during-uninstall-537423/​
​http://ftp.rpm.org/max-rpm/s1-rpm-miscellania-rpm2cpio.html​
​https://blog.packagecloud.io/eng/2015/10/13/inspect-extract-contents-rpm-packages/(what is inside rmp)
​https://www.tecmint.com/20-linux-yum-yellowdog-updater-modified-commands-for-package-mangement/​
​https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sec-configuring_yum_and_yum_repositories(yum.conf)
​https://www.quora.com/What-is-gpgcheck-in-a-yum-configuration-file-in-Rhel​
​https://www.digitalocean.com/community/tutorials/how-to-set-up-and-use-yum-repositories-on-a-centos-6-vps​
​https://superuser.com/questions/1252958/explanation-of-the-contents-inside-folder-etc-yum-repos-d​
​https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sec-working_with_yum_cache( working with yum cache)
​https://www.hivelocity.net/kb/how-to-clear-the-yum-cache/ (clear cache)