How to Determine Unique Commands for Your Linux Server

Most commands in Linux work the same as their counterparts in other UNIX applications. However, there are some commands unique to Linux that extend its functionality. In this example we are using Red Hat Linux, a popular Linux distribution that shares qualities of most other Linux variants. Here is how to determine unique commands for your Linux server.

Difficulty: Moderately Challenging

Instructions

1. Change your default shell to the Bourne-again shell (Bash). Bash is the most advanced UNIX-like shell, with the most capabilities.

2. Burn CD-ROM with the command-line driven "cdrecord" utility. It can utilize any SCSI CD writer or any IDE writer using Linux ide-scsi emulation.

3. Use the "md5sum" command to compare any two files. Two identical files will return the same md5 checksum.

4. Use the "rpm" command to install, remove and manage software packages. It is feature-filled and has become a standard for Linux systems.

5. Use the "up2date" command to automatically log in to a remote rpm server and apply package and security updates, as well as others.

6. Formatting the hard disk with the Linux ext3 file system, with its "chattr" and "lsattr" commands, can apply extended file attributes above and beyond the standard UNIX ufs attributes. For instance, "chattr +i" sets the immutable bit on a file, meaning the file cannot be deleted or changed, even by root.

7. Use the "chkconfig" and service commands to cleanly manage the /etc/rc.d run control directories and services. The alternative, on non-Linux systems, is to manually manage startup files and the run levels in which they start and stop.

Tips & Warnings

• Linux commands are very well-documented. The Linux Documentation Project is a great resource for advanced Linux documentation.
• Even the common UNIX commands such as cp and rm are extended in Linux. By default, these commands will ask for you to confirm (y/n) if you are about to overwrite or remove an existing file.
• When installing Linux, do not enable Security Enhanced Linux (SELinux) unless you are absolutely sure this is what you want. Enabling SELinux applies a very restrictive layer of security to your system that may make its management very difficult.
• If you administer many different UNIX variants, the commands can start to become confusing.