Learn Enough Linux Command Lines to be Dangerous, or to be Safe

This post lists the most commonly used commands in linux (or alike, like MacOS) system.

File System

$ whoami

prints the login name of the current user.

$ pwd

prints the current working directory (Print Working Directory)

$ ls

lists files and directories. Often used with options

• ls -l: -l option signifies the long list forma
• ls -a: -a option means list hidden files
• ls -F: -F option makes files of different types appear differently. Display a slash ('/') immediately after each pathname that is a directory, an asterisk ('*') after each that is executable, an at sign ('@') after each symbolic link etc.

$ cd 

change directory. Note often used:

• cd .. go to parent directory
• cd - go to previous directory
• cd ~ go to home directory

$ mkdir

creates a directory

$ rmdir

removes a (empty) directory

$ cp src dest 

copies files/folders from one location to another

$ mv src dest 

moves files/folders from one location to another

$ rm 

removes files/folders. Often used:

• rm -r folder_name removes a folder and its content
• rm -rf folder_name removes without prompts

Processes

$ ps

see the processes associated with the current shell. Often used with:

• ps -ef get a full listing of all processes in the system
• ps -ef | grep process_name get process_name process

top

display the processes using the most CPU time. Often used with:

• top -n 10 lists the top 10 processes that use the most CPU time

quit with q

kill 

terminates a process kill PID. Use kill -9 PID to force kill.

Misc

$ vim 

text editors for writing files.
Recommended: install plugins ultimate vim to make vim more powerful and colorful.

$ cat
$ more 
$ less

view files

$ grep

search text files

$ gcc 
$ gdb

compilers and debuggers

More

One can use man to get a detailed explanation of commands

man cp