Linux with Operating System Concepts

Option
Meaning
--excludedocs
Install without any documentation (if any of the files are explicitly listed as 
documentation); this includes omitting man pages.
--force
Force installation even if some of the files have already been installed.
--ignoresize
Do not check for sufficient disk space in given partition before installing.
--ignorearch
Perform installation even if the binary files do not match the host computer’s architecture.
--includedocs
Install documentation files; this is selected by default.
--nosignature
Do not verify signature so that errors/warnings do not arise from bad or missing signatures.
--nodeps
Install without performing dependency check; the software may install but may not run 
correctly.

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Software Installation and Maintenance
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541
Yum is also handy for upgrading software without your involvement. Whereas in RPM, 
to upgrade a package you would have to initiate the request, you can schedule yum to 
regularly search for upgrades and install them without your interaction. We examine this 
use of yum in Section 13.5.
The yum program does not require a file already downloaded to perform its task unlike 
rpm (although rpm could download the file first, if a URL is provided in place of a file 
name). With yum, instead, it searches prespecified repositories and mirror sites for the 
package named in the instruction. The yum instruction essentially has three parts:
• The command: install, update, remove, list
• The package name: this is not a file name, but a less specific software title such as gcc 
(the C compiler), emacs, httpd (the Apache web server)
• Options
For example, you might issue the command
yum install emacs
or
yum update httpd
The 
list
command does not require a package name at all. If one is provided, you 
will be given all packages that match that name. Wildcard characters of * and [] can be 
included with the package name so that globbing takes place. Two examples follow:
yum list *gnome*
yum list gimp[0-9]
The first of these will list any packages that contains “gnome” in the title. The second will 
list any packages starting with the characters “gimp” followed by a digit.
Aside from install, update, remove, and list, there are dozens of other possible com-
mands. Table 13.2 highlights a few of the more common commands. The additional 
parameters are typically either package names or filenames. As with install and list, these 
can include wildcards.
yum has a number of options although only a few are worth mentioning. First, the 
option -y (or --assumeyes) will respond ‘y’ to any “yes/no” question that yum asks. This 
allows yum to run without any user interaction. The options -d and -e set debug and 
error levels to control output. Other options control aspects of the installation such as 
--
installroot
=
dir
to alter the installation location to 
dir
as opposed to the default and 
--
enablerepo
=
repos
and --
disablerepor
=
repos
to enable and disable specific 
repositories to be or from being accessed for installation.

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542
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Linux with Operating System Concepts
Let us take a look at the output from yum. Here, we issue the command
yum –y install emacs
This command will find the emacs package in one of the repositories and begin installation 
without waiting for the user because of the –y option. The output provided is shown below 
with comments interspersed to explain what is going on.
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: ftp.linux.ncsu.edu
* extras: mirror.serversurgeon.com
* updates: mirror.linux.duke.edu
TABLE 13.2 
Yum Commands