Basic Linux Commands

Here are some basic Linux commands to get you up and running, or a quick cheat sheet. Great for when working on a Raspberry Pi or any other single board computers which use Linux commands such as Beagleboard / Beaglebone, Asus Tinker Board and many others.

FILES & NAVIGATING

• ls – directory listing (list all files/folders on a current directory)
• ls -l – directory listing, with the file details in a formatted way, easier to read
• ls -la – directory listing the same as ls -l but this will also display hidden files
• cd dir – change directory to dir (dir will be directory name)
• cd .. – change to the parent directory
• cd ../dir – change to dir in the parent directory (dir is replaced with a specific directory)
• cd – change to the home directory
• pwd – show current directory
• mkdir dir – create a directory dir (replace dir with your chosen name)
• rm file – delete a file
• rm -f dir – force remove a file
• rm -r dir – delete directory dir
• rm -rf dir – remove directory dir
• rm -rf / – if run by a superuser, will delete every file on the system (DO NOT DO THIS)
• cp file1 file2 – copy file1 to file2
• mv file1 file2 – rename file1 to file2
• mv file1 dir/file2 – move file1 to dir as file2
• touch file – create or update file
• cat file – output contents of a file
• cat > file – write standard input into a file
• cat >> file – append standard input into a file
• tail -f file – output contents of a file as it grows

NETWORKING

• ping host – ping host
• whois domain – get whois for a domain
• dig domain – get DNS for domain
• dig -x host – reserve lookup host
• wget file – download file
• wget -c file – continue a stopped download
• wget -r url – recursively download files from a URL
• curl url – outputs the webpage from a URL
• curl -o hello.html URL – writes the page to hello.html
• ssh [email protected] – connect to host as user
• ssh -p port [email protected] – connect using port
• ssh -D [email protected] – connect & use bind port

PROCESSES

• ps – display currently active processes
• ps aux – detailed outputs
• kill pid – kill process with process id (pid)
• killall proc – kill all processes named proc

SYSTEM INFORMATION

• date – show current date / time
• uptime – show uptime
• whoami – currently logged in user
• w – display who is online
• cat /proc/cpuinfo – displays CPU information
• cat /proc/meminfo – displays memory information
• free – show memory and swap usage
• du – show directory space usage
• du -sh – displays readable sizes in GB
• df – show disk usage
• uname -a – show all kernel information. Alternatively, if you only want specific information, you can change the “-a” switch to any of these for different information: “-m, -r, -v, -n”
• sudo lshw – calls the lshw tool which gathers vast information about the computer’s hardware such as CPU, disks, memory, USB controllers etc
• lscpu – display CPU information
• lsusb – displays USB controllers information
• lspci – displays PCI devices information

COMPRESSING

• tar cf file.tar files – tar files into file.tar
• tar xf file.tar – untar into a current directory
• tar tf file.tar – show contents of archive
  • Switches:
    • c – create an archive
    • t – table of contents
    • x – extract
    • z – use zip/gzip
    • f – specify a filename
    • j – bzip2 compression
    • w – ask for confirmation
    • k – do not overwrite
    • T – files from a file
    • v – verbose

PERMISSIONS

• chmod octal file – change permissions of a file
  • 4 – read (r)
  • 2 – write (w)
  • 1 – execute (x)

order owner/group/world

• chmod 777 -rwx for everyone
• chmod 755 – rw for the owner, rx for group world

OTHER USEFUL COMMANDS

• grep pattern files – search in files for a pattern
• grep -r pattern dir – search for pattern recursively in dir
• locate file – find all instances of a file
• whereis app – show possible locations of app
• man command – show manual page for a command