GNU/Linux Getting started with GNU/Linux Basic Linux Utilities


Linux has a command for almost any tasks and most of them are intuitive and easily interpreted.

Getting Help in Linux

man <name>Read the manual page of <name>.
man <section> <name>Read the manual page of <name>, related to the given section.
man -k <editor>Output all the software whose man pages contain <editor> keyword.
man -K <keyword>Outputs all man pages containing <keyword> within them.
apropos <editor>Output all the applications whose one line description matches the word editor. When not able to recall the name of the application, use this command.
helpIn Bash shell, this will display the list of all available bash commands.
help <name>In Bash shell, this will display the info about the <name> bash command.
info <name>View all the information about <name>.
dpkg -lOutput a list of all installed packages on a Debian-based system.
dpkg -L packageNameWill list out the files installed and path details for a given package on Debian.
dpkg -l | grep -i <edit>Return all .deb installed packages with <edit> irrespective of cases.
less /var/lib/dpkg/availableReturn descriptions of all available packages.
whatis vimList a one-line description of vim.
<command-name> --helpDisplay usage information about the <tool-name>. Sometimes command -h also works, but not for all commands.

User identification and who is who in Linux world

hostnameDisplay hostname of the system.
hostname -fDisplays Fully Qualified Domain Name (FQDN) of the system.
passwdChange password of current user.
whoamiUsername of the users logged in at the terminal.
whoList of all the users currently logged in as a user.
wDisplay current system status, time, duration, list of users currently logged in on system and other user information.
lastWho recently used the system.
last rootWhen was the last time root logged in as user.
lastbShows all bad login attempts into the system.
chmodChanging permissions - read,write,execute of a file or directory.

Process related information

topList all processes sorted by their current system resource usage. Displays a continually updated display of processes (By default 3 seconds). Use q key to exit top.
psList processes currently running on current shell session
ps -u rootList all of the processes and commands root is running
ps auxList all the processes by all users on the current system