Linux Commands

Saturday, October 06, 2012    

Linux Commands

Are you looking for Linux Cheat Sheet? Or most used linux commands? I am putting up a list below for my own reference that could come in handy to you as and when you need it. I hope you like it!

 

 

System Info

  • date – Display current date and time
  • cal – show current month’s calender
  • uptime – show current server’s uptime since last reboot
  • w – display which user’s are logged in and average load on the server
  • whoami – who you are logged in as (funny!)
  • finder username – Get information about A specific user on the system
  • uname – a – Display kernal information
  • cat /proc/cpuinfo – Display CPU information
  • cat /proc/meminfo – Display Memory (RAM) info
  • man command – Show Manual for any “command”
  • df – show disk usage
  • du – show directory space usage
  • df -h – show all HDD’s and their mount point
  • free – show RAM and its swap usage (free -m to display in MB)
  • whereis app – Find location of an app

Network

  • ping – ping any IP / Host and output result
  • whois domain.tld – Get whois information of any domain name
  • dig domain.tld – Get DNS information of any domain
  • dig -x host – Reverse lookup
  • wget file-location – Download any remote file
  • wget -c file – Continue a paused / stopped download

File Commands

  • ls – List directories
  • ls -al – Formatted listing with hidden files
  • cd dir – Change to DIR
  • cd – Switch to home
  • pwd – Show current directory
  • mkdir name – Create a new directory called “name”
  • rm filename – Delete a file
  • rm -r dir – Delete an EMPTY directory called “dir”
  • rm -rf dir – Delete an entire directory with files called “dir”
  • cp file1 file2 – Copy file1 to file2
  • mv file1 file2 – Move or Rename a file
  • touch file – Create or Update a file
  • more file – Output the content of the file
  • tail file – Output last 10 lines of a file

Compression

  • tar cf file.tar files – Create a tarball compressing the folder called “files”
  • tar xf file.tar – Exact the tarball “file.tar”
  • gzip filename  - Compress and rename the file to filename.gz

File Permissions

  • 4 – Read (r)
  • 2- Write (w)
  • 1- Execute (x)
  • Example : “chmod 777 filename” will allocation read, write & execute permission to filename.

Searching

  • grep pattern files – search for a pattern in files
  • grep -r pattern dir – Search recursively for pattern in dir
  • command | grep pattern – Search for pattern in output command
  • locate file – Find all instances of file

Process Management

  • ps – Display all current active processes
  • top – Display all running processes
  • top -c – Display processes using top CPU
  • top -m – Display processes using top Memory (RAM)
  • kill pid – Kill a process with its pid
  • bg – List stopped background jobs
  • fg – Bring the most recent job to the foreground

SSH

  • ssh user@hostname – connect to a host as a user
  • ssh -p 22 user@host – Connect to a host as a user on specific port (in this case 22)
  • ssh-copy-id user@host – Add your key to host for user to enable a keyed or password-less login

Shortcuts

  • Ctrl + C – Halts the current command
  • Ctril + Z – Stops the current command, you can resume it with fg in the foreground and bg in the background
  • Ctril + D – Logout of current session
  • Ctrl + U – Erase the line
  • Ctrl + R – Type to bring up a recent command
  • !! – Repeat the last command
  • exit – Logout of current session
  • abc* – Every file / dir / etc starting with abc

I hope you liked the sheet and will make use of it. In case you think I have forgotten anything, feel free to add it in the command and I will get the main sheet updated.