Sallar
RedhatEnterpriseLinux Blog
Understanding How RPM Works
How does RPM work? Each software program consists of files and
directories, most of which must be located in a particular place on the
filesystem. If the software program is distributed in RPM format, these files
are compressed together into one RPM file along with instructions on where the
files should be located on the filesystem and any additional scripts or
executables that must be run before or after the files are installed. These RPM
files are often referred to as packages.
A software program, such as the Firefox web browser, might consist
of one RPM file. However, some programs are divided into multiple RPM files to
allow the administrator to customize which parts are necessary for the system’s
usage. For example, the GNOME graphical desktop is divided into many packages
that contain parts of the overall desktop.
How to Finds File in linux
There are two invaluable commands that can be
used to find files on the filesystem: locate
and find. The locate command
is the easier of the two to use. Just type the command followed by part or all
of the filename you are searching for such as locate .odt to find all
OpenOffice.org text files or locate
compare to find all
filenames that contain the word compare. Notice that no wildcard
characters are used. It is assumed that what you type may only be part of the
filename you are looking for.
The only catch to this command is that it
relies on the generation of a database file so it can quickly display results.
The locate command is provided by the mlocate
package, which also provides the cron
script /etc/cron.daily/mlocate.cron to
How to Find Commands
If you know a command exists on the system but keep getting the
error message command not found, check to make sure you are typing the command correctly.
Otherwise, it might not be in your PATH environment variable. To view the value of your PATH, execute the command echo $PATH from the command line. As you can see, your PATH
is a list of directories. When you execute a
command without providing its full path, it must be in one of the directories
listed in your PATH. Otherwise,
the command not found error is displayed. You
can provide the full path to the command if you know it, such as /sbin/lspci
to execute the command to list the PCI
devices. If you use the command often, but it is not in your PATH, you can add the directory to your PATH.
How to Read Text Files in linux
Sometimes you want to quickly read a text file such as a
configuration file without having to open a text editor. This is possible with
the less, more, and cat command-line
utilities. All three have the same basic syntax but work differently and have
different commandline options. To use them in their default modes, type the
command followed by the text file to read such as less
output.txt, more /var/loasg/messages, or cat
/etc/sysconfig/ network.
How to Become the Root User
It is important to log in with your user account instead of as the
root user when performing day-to- day tasks. Some of the graphical
administration tools will prompt you for the root password if you try to run
them as a regular user. But, what if you are logged in as a user and need to
perform an operation only the root user can do? It would be time consuming to
close all your open windows, log out of the graphical desktop, log back in as
root, execute root-only commands, log out again, and then log back in with your
user account.
How to Configure Service Configuration Tool
To immediately start, stop, or restart a service, select it from
the list and click the Start, Stop, or Restart button. This does not affect whether it is started or stopped at
boot time. If you do not have the graphical desktop installed or just prefer a
more simplistic interface, ntsysv can be used to configure runlevels. The program must be run as the
root user.
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