Linux CLI Notes

A personal cheat sheet for Linux command line essentials.
Organised by topic, with commands, descriptions, and examples.
Updated as I progress through The Linux Command Line book.

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Navigation

• cd – Change directory

  cd ..         # go up one directory
  cd /etc       # go to /etc
  cd /usr/bin   # go to /usr/bin
  cd ~ 			# go to current users home
  cd ~$USER     # go to specified user home

• ls – list directories and files

  ls -l   		# long list format
  ls -la  		# include hidden files
  ls -li  		# show inode numbers

• pwd – print current directory

  pwd 			# prints the current (working) directory

File Control and Manipulation

• mkdir – create a directory

  mkdir (name)	# creates a new directory with a given name

• touch – create a file

  touch (name) 	# creates a new file with a given name

• rm – removes files/directories

  rm (name)    	# deletes files/directories 

• nano – opens a file in a text editor

  nano (name)  	# opens a file in a text editor. creates one if !file

• cp – make a copy of a file or directory

  cp src dest  	# copy files/directory 

• mv – opens a file in a text editor

  mv old new  	# opens a file in a text editor. creates one if !file

Searching

• find – find a file or directory on the host machine

  find 					# will search for a directory and or File
    Options - find 'dir'
    		- find file 
    		- find dir file 

• grep – find matching strings

  grep 							# find matching strings in a file or directory name, as well as matching strings in a files content
  grep -i 						# ignore case sensitivity
  grep -r text dir				# search recursively in directory

Linking

• ln – create a link

  ln link_file link_to_file		 # creates a hard link 
  ln -s /path/target symlink-name		# creates a symbolic link

Output and Redirection

• > – Redirect stdout to file (overwrite)

  cat /path/target > output.txt

• >> – Redirect stdout to file (append)

  cat /path/target >> output.txt

• 2> – Redirect stderr (overwrite)

  cat /path/target 2> errors.txt

• 2>> – Redirect stderr (append)

  cat /path/target 2>> errors.txt

• &> – Redirect stdout and stderr (overwrite)

• | – Pipe output to another command

  cat file | grep string | wc 

• tee – Write to file and stdout

  cat file | tee | grep string | 

Help & Documentation

• man – Manual pages

1 = user commands

2 = system calls

3 = C library functions

4 = special files (device nodes, drivers)

5 = file formats

6 = games

7 = misc

8 = admin commands

whatis – One line descriptor