Common Linux Commands

Posted by Tully on Wed 06 May 2009

halt

This command shuts down the operating system, but can only be run by the root user.

reboot

This command shuts down and restarts the operating system. It also can only be run by root.

init 0

This command also shuts down the operating system, and can only be run by the root user.

init 6

This command also shuts down and restarts the operating system. It also can only be run by root.

man

This command opens the manual page for the command or utility specified. The man utility is a very useful tool. If you are unsure how to use any command, use man to access its manual page. For example, you could enter man ls at the shell prompt to learn how to use the ls utility.

info

The info utility also displays a help page for the indicated command or utility. The information displayed tends to be more in-depth than that displayed in the man page for the same command.

su

This command switches the current user to a new user account. For example, if you're logged in as tully and need to change to user account brett, you can enter su brett at the shell prompt. This command is more frequently used to switch to the superuser root account. In fact, if you don't supply a username, this utility assumes that you want to change to the root account. If you enter su, then you will switch to the root user account and have all of root's environment variables applied.

env

This command displays the environment variables for the currently logged-in user.

echo

This command is used to echo a line of text on the screen. It's frequently used to display environment variables. For example, if you wanted to see the current value of the PATH variable, you could enter echo $PATH.

top

This command is a very useful command that displays a list of all applications and processes currently running on the system. You can sort them by CPU usage, memory usage, process ID number, and which user owns them.

which

This command is used to display the full path to a shell command or utility. For example, if you wanted to know the full path to the ls command, you would enter which ls.

whoami

This command displays the username of the currently logged-in-user.

netstat

This command displays the status of the network, including current connections, routing tables, etc.

route

This command is used to view or manipulate he system's routing table.

ifconfig

This command is used to manage network boards installed in the system. It can be used to display or modify your network board configuration parameters. This command can only be run by the root user.