linux : basic commands

Linux is closely related to the command line. Even though some people prefer to use graphic user interface (GUI), we will using command-line interface (CLI). CLI is more effective and powerful. Some process can be done in one line of commands in seconds.

These some basic commands that I use often.

1. Navigation

• pwd : print working directory
• cd : change directory
  • cd : go to home
  • cd {dir_path} : go to directory path
  • cd .. : on directory above
  • cd - : back to last directory path
• ls : list
  • ls -a : list all (include hidden file and folder)
  • ls -l : long list
  • ls -la : long list all

---

2. Directory / file management

• touch : create a new file
• mkdir : create a new folder
• rm : remove
  • rm {file_name} : delete a file
  • rm -r {dir_name} : delete a folder
• rmdir : remove directory, only allows to delete empty directory
• cp : copy
  • cp {old_file} {new_file} : copy a file
  • cp -r {old_dir} {new_dir} : copy a folder and all sub folder
• mv : move
  • mv {old_file_path} {new_file_path} : move a file or folder
  • mv {old_file_name} {new_file_name} : rename a file or folder
• locate {file_name} : search a file or folder
  • locate -i {file_name} : search file with case-insensitive
• find {dir_path} {file_name} : search a file or folder inside a directory
• tar : archive multiple files into a tarball
• zip : compress files into a zip archive
• unzip : extract the zipped files

---

3. File view and editing

• nano : view and edit with nano
• vim : view and edit with vim
• cat : view file
  • cat > {file_name} : create a new file
  • cat {file_1} > {file_2} : copy file 1to file 2
  • cat {file_1} >> {file_2} : append file 1 content to file 2
• grep {keyword} {file_name} : search through all the text in a given file
• head : view the first lines of any text file, by default it will showing first 10 lines
  • head -n 5 {file_name} : display first 5 lines of the file
• tail : view the last lines of any text file, by default it will showing - first 10 lines
  • tail -n 5 {file_name} : display last 5 lines of the file

---

4. Manual guide

• man : manual
  • man cp : display full guide for copy command
• --help : help
  • cp --help : display short guide for copy command

---

5. System commands

• sudo : SuperUser Do, enables to perform tasks that require administrative or root permissions
• command1; command2; command3 : run multiple commands
• command1 && command2 && command3 : run the next commands after the first one is successful
• useradd {username} : add a new user
  • passwd {password} : set the password
• userdel : delete a user
• chmod {options} {file_name} : change the read, write, and execute permissions of files and directories
  • chmod u=rwx,g=rx,o=r {file_name}
  • u : user
  • g : group
  • o : other
  • r : read
  • w : write
  • x : execute
• chown {username} {file_name} : change or transfer the ownership of a file
• uname : print detailed information about your Linux system
• hostname : display the name of host/network
  • hostname -i : display the IP address of the network
• wget {link} : download from the internet
• ps : display information about the currently running processes, including their process identification numbers (PIDs)
• kill {pid} : terminate an unresponsive program
• df : get a report on the system’s disk space usage
  • df -h : display disk space statistics
  • df -m : display disk space statistics in megabytes
• du -h : display disk usage
• free -m : show free memory
• cat /proc/cpuinfo : display cpu info
• htop / top : monitor system resources
• history : review the commands we’ve entered before
• clear : clean out the terminal

---

6. Keyboard shourcut

• ctrl + C : safe kill
• ctrl + Z : sometimes there are child processes that still running in the background
• ctrl + A : moves to the beginning of the line
• ctrl + E : moves to the end of the line

---