Command line one-liners

After my article about command line one-liners, many people want to contribute with their own commands. This is the place to do it, pull requests are welcome!

Table of Contents

• History
• Directories
• Files
• Searching
• Networking
• User environment
• File system
• Date & Time
• Processes
• Miscellaneous

---

History

• Run the last command

  $ !!
  

• Run the last command as root

  $ sudo !!
  

• Create a script of the last executed command

  $ echo "!!" > script.sh
  

• Reuse all parameter of the previous command line

  $ echo cd .
  $ !*
  

• Run the last command with some argument

  $ echo a b c d e
  $ echo !!:2
  $ echo !!:3-$
  

• Insert the last argument of the previous command

  $ cp script.sh /usr/bin/
  $ cd !$
  $ cd <ESC> .
  $ cd <ALT> .
  

• Runs previous command but replacing

  $ echo no typos
  $ ^typos^errors
  

• Escape any command aliases

  $ alias ls="ls -a"
  $ \ls
  

• Run a command from the history

  $ history
     ...
     1225  ls -l
     1226  git status
     1227  history
  $ !-3
  $ !1225
  

• Search the history for the most recent command beginning with text

  $ !text
  

• Search the history for the most recent command containing text

  $ <ctrl-r>text
  

• List of commands you use most often

  $ history | awk '{print $2}' | sort | uniq -c | sort -rn | head
  

• Execute a command without saving it in the history

  $ <space>command
  

Directories

• Make a directory creating intermediate directories

  $ mkdir -p a/long/directory/path
  

• Create a directory and change into it

  $ mkdir dir && cd $_
  

• Change to the previous working directory

  $ cd -
  

• Jump to a directory. Execute a command in a subshell. Jump back to current directory

  $ (cd /tmp && ls)
  

Files

• Quickly rename a file

  $ mv filename.{old,new}
  $ mv filename.{png,jpg}
  

• Create a quick back-up copy of a file

  $ cp file.txt{,.bak}
  

• Create a simple text file from command line

  $ cat > file.txt
  {your text here}
  {your text here}
  <ctrl-d>
  

• Create a simple text file from command line or script (EOF is just a token, can be any word)

  $ cat > file.txt << EOF
  {your text here}
  {your text here}
  EOF
  

• Empty a file from command line (usefull to truncate log file from running processes)

  $ > file.txt
  

• Empty a file from command line or script

  $ cat /dev/null > file.txt
  

• Make less behave like tail -f

  $ less +F somelogfile
  

• Display line numbers in a file

  $ cat -n file
  $ less -N file
  

• Redirect standard input to a file. Print it to standard output

  $ command | tee file.txt | less
  
    ┌─────────┐  ┌─────────┐  ┌─────────┐
    │ command │─▸│   tee   │─▸│ stdout  │
    └─────────┘  └────┬────┘  └─────────┘
                      │
                      ▾
                ┌───────────┐
                │   file    │
                └───────────┘
  

Searching

• Search for a string inside all files in the current directory

  $ grep -RnsI --color=auto <pattern> *
  

• Beyond grep

    _   /|
    \'o.O'
    =(___)=
      U    ack!
  
  $ ack <pattern>
  

• Recursively remove all empty directories

  $ find . -type d -empty -delete
  

Networking

• Serve current directory tree at http://$HOSTNAME:8000/

  $ python -m SimpleHTTPServer
  $ ruby -run -e httpd . -p 8000
  

• Share a file between two computers

  receiver $ nc -l 5566 > data-dump.sql
  sender   $ nc <receiver-ip-address> 5566 < data-dump.sql
  

• Share a BIG file between two computers and show progress bar

  receiver $ nc -l 5566 > big-file.iso
  sender   $ pv big-file.iso | nc <receiver-ip-address> 5566
  

• Transfer a folder between two computers

  receiver $ nc -l 5566 | tar -zxv
  sender   $ tar -zcv <folder> | nc -w1 <receiver-ip-address> 5566
  

• Download an entire website

  $ wget -m -k http://website.com
  

User environment

• Show PATH in a human-readable way

  $ echo $PATH | tr ':' '\n'
  $ tr ':' '\n' <<< $PATH
  

• Clear the terminal screen

  $ <ctrl-l>
  $ clear
  

• Salvage a borked terminal

  $ reset
  

• Close shell keeping all subprocess running

  $ disown -a && exit
  

• Run a command immune to hangups

  $ nohup command &
  

Networking

• Attach screen over ssh

  $ ssh user@host -t screen -r
  

• Compare a remote file with a local file

  $ ssh user@host cat /path/to/remotefile | diff /path/to/localfile -
  

• Get your public IP address

  $ curl ifconfig.me
  

• Set audible alarm when an IP address comes online

  $ ping -a IP_address
  

• List programs with open ports and connections

  $ lsof -i
  

• Check which process is listening on a specific port

  $ netstat -nlp | grep 8080
  $ netstat -nlp tcp | grep 8080 (BSD)
  

File system

• Currently mounted filesystems in nice layout

  $ mount | column -t
  

• Display free disk space

  $ df -h
  

• Display disk usage statistics for the current directory

  $ du -sh *
  

• Display 10 biggest files/folders for the current directory

  $ du -s * | sort -nr | head
  

• Create a zip archive of a directory

  $ zip -r archive.zip directory
  

• Extract compressed archive

  $ unzip archive.zip
  

• Show File System Hierarchy

  $ man hier
  

Date & Time

• Shutdown the system at a given time

  $ shutdown -h now
  $ shutdown -h 22:49
  

• Execute a command at a given time

  $ echo "ls -l" | at midnight
  

• Simple stopwatch

  $ time read
  <ctrl-d>
  

• Put a console clock in top right corner

  $ while sleep 1;do tput sc;tput cup 0 $(($(tput cols)-29));date;tput rc;done &
  

• Displays a calendar

  $ cal 12 1984
  

• What day was yesterday or will it be tomorrow, etc...

  $ date -d yesterday
  $ date -d tomorrow +%Y-%m-%d
  $ date -d "7 days ago" +%Y-%m-%d
  $ date -j -v-1d (BSD)
  

Processes

• Display the top ten running processes. (Sorted by memory usage)

  $ ps aux | sort -nk +4 | tail
  

• Kill all Ruby processes

  $ ps aux | grep ruby | awk '{ print $2 }' | xargs kill -9
  $ ps aux | awk '/ruby/ && ! /awk/ { system("kill -9 "$2) }'
  $ pkill -f ruby
  $ killall -9 ruby
  

• Check which process is modifying a certain directory or file

  $ auditctl -w /path/to/directory -p war
  

  See results

  $ ausearch -f /path/to/directory
  

Miscellaneous

• 32 bits or 64 bits?

  $ getconf LONG_BIT
  

• Quick access to the ascii table

  $ man ascii
  

• Count your commits

  $ git shortlog -sn
  

• Russian Roulette in Bash (remember kids don't try this at home)

  $ [ $[ $RANDOM % 6 ] == 0 ] && rm -rf / || echo "You live"
  

• Watch Star Wars via telnet

  $ telnet towel.blinkenlights.nl
  

Who made this?

This was made by Arturo Herrero under the MIT License. Find me on Twitter @ArturoHerrero.