Selected, commonly used tools:

• pwd - returns current working directory
• ls - lists files and directories

  Allows to list files and directories

  Description	Command	Notes
  Shows files and directories in current directory	ls
  Shows files and directories in current directory as a list	ls -l
  Shows files and directories in current directory with sizes in human-readable format	ls -h

• df - reports file system disk space usage

  Description	Command	Notes
  Disk space usage	df
  Disk space usage in human-readable format	df -h	Human-friendly refers to using KB/MB/GB/TB units
  inode usage	df -i	Programs can't write to filesystem without free inodes
  Disk space usage with file system type	df -T

• du - reports file system disk usage

  Description	Command	Notes
  Disk usage at specific path	du
  Disk space at specific path - count sums for directories	du -c
  Disk space at specific path - display output in human-friendly format	du -h	Human-friendly refers to using KB/MB/GB/TB units
  Disk space sum at specific path	du -s

• cp - copies files/directories

  Description	Command	Notes
  Copy file input to output	cp input output
  Recursively copy files from input to output	cp -r input output	This switch is commonly used to copy all subdirectories and files within

• mv - moves files/directories

  Description	Command	Notes
  Move file input to output	mv input output

• rm - removes files/directories

  Description	Command	Notes
  Removes file	rm file	❗ This command is dangerous
  Removes files recursively in path	rm -r path	❗ This command is extremely dangerous

• grep - searches for string in files

  Description	Command	Notes
  Find string in files in current directory	grep string *
  Find string in files in current directory or its subdirectories	grep -r string *
  Find string in files in current directory and display line number	grep -n string *
  Find whole-word string in files in current directory	grep -w string *
  Find regular expression string in files in current directory	grep -e string *

• chown - changes file owner and group

  Description	Command	Notes
  Change file owner to user	chown user file
  Change file owner to user and group to group	chown user:group file
  Change directory owner to user for directory and its subdirectories	sudo chown -R user directory

• chmod - changes file permissions

  Permissions are typically noted by 3 numbers; leftmost being user, middle being group and rightmost being others.

  Number on each position is a sum of desired permissions: 4 (read), 2 (write) and 1 (execute).

  Note that directories require execution permission to be opened!

  Description	Command	Notes
  Make file permissions	chmod +x file
  Change file permissions to 600 (owner only read/write)	chmod 600 file
  Recursively change files permissions	chmod -R 600 directory

• find - searches for files or directories

  Description	Command	Notes
  Search for file with string in name	find -name "*string*" -type f
  Search for directories with string in name	find -name "*string*" -type d

• sudo - executes as root

  Allows executing other commands as root. Operating as root is considered a bad practice and can lead to system instability - even without any mistakes!

  Description	Command	Notes
  Shows sudo usage	sudo
  Executes cmd as root	sudo cmd	❗ Depending on cmd it's either harmless or (on setups with bad UEFI implementation) instantly breaks hardware
  Executes cmd as user	sudo -u user cmd

Last update: 2024-06-12