Linux Basic Commands List

Basic Linux Commands

# tty Shows the current logged in terminal

# whoami shows the currently logged in user

# which "command name"  reveals where in the search path a program is located

# echo prints to the screen

# echo $PATH  dumps the current path to STDOUT

# echo $PWD     dumps ths contents of the $PWD variable

# echo $OLDPWD  dumps the most recently visited directory

# clear         clears the screen or terminal

# reset         resets the screen buffer

# history       reveals your command history

# !110  executes the 110th command in our history

Files and Directories

# ls             list the files and directories in the present working directories

# ls -ltr        sort the files in the last modification time in reverse order

# ls -a          list all the files including hidden files and directories ( all files starting with "." are hidden files)

# ls -l          long list of all files and directories where you can check the relative 

permission on each file.

# mkdir "directory name"                 Create directory

# mkdir -p /"dir1"/"dir2"/"dir3"/        Create directory including parent dir

# touch "filename"                       Create files

# cp "dir1"  /root/    copy directory or file to another location

# mv dir1  /root/      move or rename the dir or file to different location

# rm "dir name"        To remove directory

# rm -rf "dir name"    To remove a directory recursively and forcefully

For further switches to be used with any of the above commands you can check using

# man "command name"

# "command name" --help

For example:

# rm --help

# mkdir --help

# ls --help

# cd            with no options changes to the $HOME directory

# cd ~          changes to the $HOME directory

# cd /          changes to the root of the file system

# cd Desktop/   changes us to the relative directory 'Desktop'

# cd ..         changes us one-level up in the directory tree

# cd ../..      changes us two-levels up in the directory tree

User and Group related

# useradd "username"                      creates a user

# passwd "username"                       Assign password to user

# groupadd "groupname"                    creates a group

# usermod -a -G "groupname" "username"    Add existing user to group

# groupmod -A username groupname          Add existing user to group

# useradd -d "directory name" -s "shell" -g "group name" -u "UID" "username"                                 Creates user with provided details

Command chain

# head /var/log/messages      displays opening lines of text files

# head -10 /var/log/messages  displays opening 10 lines of text files

# tail /var/log/messages      displays the closing lines of text files

# tail -10 /var/log/messages  displays the closing 10 lines of text files

# wc -l /var/log/messages     counts words and optionally lines of text files