CHEATSHEET: Linux Core Utility Commands

Simple Commands

• date - displays the current time and date
• cal - displays a calendar of the current month
• df - displays the current amount of free space on our disk drives
• free - displays the amount of free memory
• clear - clear the terminal screen
• history - display or manipulate the history list
• exit - ends a terminal session

Navigation Commands

• pwd - display the current working directory
• cd - change current working directory to another specified directory

Linux Path names

Linux path names can be specified in the following two ways:

• absolute path names - specify the path name from the root (/) directory
• relative path names - specify the path name from the current directory using dot notation
  • . - refers to the current directory
  • .. - refers to the parent directory of the current directory
  • ~ - refers to the current user’s home directory

Filesystem commands

• file - determine file type
• less - view contents of a file
• ls - list files and directories in a specific directory

ls common arguments

• -a - lists all files
• -h - display file sizes in human-readable format
• -l - display long format results
• -s - sort by file size, largest first
• -t - sort by modified time, newest first

Manipulating Files and Directories

• cp - copy files and directories
• mv - move/rename files and directories
• mkdir - create directories
• rm - remove files and directories
• ln - create hard and symbolic links
• alias - create an alias for a command. Use unalias to remove an aliased command
• touch - create a new file
• tar - used to bundle, compress and uncompress files and folders

cp, mv & rm common arguments

• -a - copy the files and directories and all of their attributes
• -i - before overwriting an existing file, prompt the user for confirmation
• -r - recursively copy directories and their contents
• -u - when copying, only copy files that don’t exist or are newer than the existing corresponding files in the destination directory
• -v - display informative messages as the copy is performed

Getting help

• type - indicate how a command name is interpreted
• which - display which executable program will be executed
• help - get help for shell builtins
• man - display a command’s manual page
• apropos - display a list of appropriate commands
• info - display a command’s info entry
• whatis - display one-line manual page descriptions

Parsing Text

• echo - display a line of text
• cat - concatenate files to the standard output
• sort - sort lines of text
• uniq - report or omit repeated lines
• grep - print lines matching a pattern
• wc - print newline, word and byte counts for each file
• head - output the first part of a file
• tail - output the last part of a file

Permissions

• id - display user identity
• chmod - change a file’s mode
• umask - set the default file permissions
• su - run a shell as another user
• sudo - execute a command as another user
• chown - change a file’s owner
• chgrp - change a file’s group ownership
• passwd - change a user’s password

Processes

• ps - report a snapshot of current processes
• top - display tasks
• jobs - list active jobs
• bg - place a job in the background
• fg - place a job in the foreground
• kill - send a kill signal to a process
• killall - kill processes by name
• shutdown - shut down or reboot the system