!! # Run the last command touch foo.sh chmod +x !$  # !$ is the last argument of the last command i.e. foo.sh 

pwd # Print current directory path ls # List directories ls -a|--all # List directories including hidden ls -l # List directories in long form ls -l -h|--human-readable # List directories in long form with human readable sizes ls -t # List directories by modification time, newest first stat foo.txt # List size, created and modified timestamps for a file stat foo # List size, created and modified timestamps for a directory tree # List directory and file tree tree -a # List directory and file tree including hidden tree -d # List directory tree cd foo # Go to foo sub-directory cd # Go to home directory cd ~ # Go to home directory cd - # Go to last directory pushd foo # Go to foo sub-directory and add previous directory to stack popd # Go back to directory in stack saved by `pushd` 

mkdir foo # Create a directory mkdir foo bar # Create multiple directories mkdir -p|--parents foo/bar # Create nested directory mkdir -p|--parents {foo,bar}/baz # Create multiple nested directories mktemp -d|--directory # Create a temporary directory 

cp -R|--recursive foo bar # Copy directory mv foo bar # Move directory rsync -z|--compress -v|--verbose /foo /bar # Copy directory, overwrites destination rsync -a|--archive -z|--compress -v|--verbose /foo /bar # Copy directory, without overwriting destination rsync -avz /foo username@hostname:/bar # Copy local directory to remote directory rsync -avz username@hostname:/foo /bar # Copy remote directory to local directory 

rmdir foo # Delete non-empty directory rm -r|--recursive foo # Delete directory including contents rm -r|--recursive -f|--force foo # Delete directory including contents, ignore nonexistent files and never prompt 

touch foo.txt # Create file or update existing files modified timestamp touch foo.txt bar.txt # Create multiple files touch {foo,bar}.txt # Create multiple files touch test{1..3} # Create test1, test2 and test3 files touch test{a..c} # Create testa, testb and testc files mktemp # Create a temporary file 

echo "foo" > bar.txt # Overwrite file with content echo "foo" >> bar.txt # Append to file with content ls exists 1> stdout.txt # Redirect the standard output to a file ls noexist 2> stderror.txt # Redirect the standard error output to a file ls 2>&1 out.txt # Redirect standard output and error to a file ls > /dev/null # Discard standard output and error read foo # Read from standard input and write to the variable foo 

cp foo.txt bar.txt # Copy file mv foo.txt bar.txt # Move file rsync -z|--compress -v|--verbose /foo.txt /bar # Copy file quickly if not changed rsync z|--compress -v|--verbose /foo.txt /bar.txt # Copy and rename file quickly if not changed 

rm foo.txt # Delete file rm -f|--force foo.txt # Delete file, ignore nonexistent files and never prompt 

cat foo.txt # Print all contents less foo.txt # Print some contents at a time (g - go to top of file, SHIFT+g, go to bottom of file, /foo to search for 'foo') head foo.txt # Print top 10 lines of file tail foo.txt # Print bottom 10 lines of file open foo.txt # Open file in the default editor wc foo.txt # List number of lines words and characters in the file 

ls -l /foo.sh # List file permissions chmod +100 foo.sh # Add 1 to the user permission chmod -100 foo.sh # Subtract 1 from the user permission chmod u+x foo.sh # Give the user execute permission chmod g+x foo.sh # Give the group execute permission chmod u-x,g-x foo.sh # Take away the user and group execute permission chmod u+x,g+x,o+x foo.sh # Give everybody execute permission chmod a+x foo.sh # Give everybody execute permission chmod +x foo.sh # Give everybody execute permission 

type wget # Find the binary which wget # Find the binary whereis wget # Find the binary, source, and manual page files 

updatedb # Update the index locate foo.txt # Find a file locate --ignore-case # Find a file and ignore case locate f*.txt # Find a text file starting with 'f' 

find /path -name foo.txt # Find a file find /path -iname foo.txt # Find a file with case insensitive search find /path -name "*.txt" # Find all text files find /path -name foo.txt -delete # Find a file and delete it find /path -name "*.png" -exec pngquant {} # Find all .png files and execute pngquant on it find /path -type f -name foo.txt # Find a file find /path -type d -name foo # Find a directory find /path -type l -name foo.txt # Find a symbolic link find /path -type f -mtime +30 # Find files that haven't been modified in 30 days find /path -type f -mtime +30 -delete # Delete files that haven't been modified in 30 days 

grep 'foo' /bar.txt # Search for 'foo' in file 'bar.txt' grep 'foo' /bar -r|--recursive # Search for 'foo' in directory 'bar' grep 'foo' /bar -R|--dereference-recursive # Search for 'foo' in directory 'bar' and follow symbolic links grep 'foo' /bar -l|--files-with-matches # Show only files that match grep 'foo' /bar -L|--files-without-match # Show only files that don't match grep 'Foo' /bar -i|--ignore-case # Case insensitive search grep 'foo' /bar -x|--line-regexp # Match the entire line grep 'foo' /bar -C|--context 1 # Add N line of context above and below each search result grep 'foo' /bar -v|--invert-match # Show only lines that don't match grep 'foo' /bar -c|--count # Count the number lines that match grep 'foo' /bar -n|--line-number # Add line numbers grep 'foo' /bar --colour # Add colour to output grep 'foo\|bar' /baz -R # Search for 'foo' or 'bar' in directory 'baz' grep --extended-regexp|-E 'foo|bar' /baz -R # Use regular expressions egrep 'foo|bar' /baz -R # Use regular expressions 

sed 's/fox/bear/g' foo.txt # Replace fox with bear in foo.txt and output to console sed 's/fox/bear/gi' foo.txt # Replace fox (case insensitive) with bear in foo.txt and output to console sed 's/red fox/blue bear/g' foo.txt # Replace red with blue and fox with bear in foo.txt and output to console sed 's/fox/bear/g' foo.txt > bar.txt # Replace fox with bear in foo.txt and save in bar.txt sed 's/fox/bear/g' foo.txt -i|--in-place # Replace fox with bear and overwrite foo.txt 

ln -s|--symbolic foo bar # Create a link 'bar' to the 'foo' folder ln -s|--symbolic -f|--force foo bar # Overwrite an existing symbolic link 'bar' ls -l # Show where symbolic links are pointing 

zip foo.zip /bar.txt # Compress bar.txt into foo.zip zip foo.zip /bar.txt /baz.txt # Compress bar.txt and baz.txt into foo.zip zip foo.zip /{bar,baz}.txt # Compress bar.txt and baz.txt into foo.zip zip -r|--recurse-paths foo.zip /bar # Compress directory bar into foo.zip 

gzip /bar.txt foo.gz # Compress bar.txt into foo.gz and then delete bar.txt gzip -k|--keep /bar.txt foo.gz # Compress bar.txt into foo.gz 

tar -c|--create -z|--gzip -f|--file=foo.tgz /bar.txt /baz.txt # Compress bar.txt and baz.txt into foo.tgz tar -c|--create -z|--gzip -f|--file=foo.tgz /{bar,baz}.txt # Compress bar.txt and baz.txt into foo.tgz tar -c|--create -z|--gzip -f|--file=foo.tgz /bar # Compress directory bar into foo.tgz 

unzip foo.zip # Unzip foo.zip into current directory 

gunzip foo.gz # Unzip foo.gz into current directory and delete foo.gz gunzip -k|--keep foo.gz # Unzip foo.gz into current directory 

tar -x|--extract -z|--gzip -f|--file=foo.tar.gz # Un-compress foo.tar.gz into current directory tar -x|--extract -f|--file=foo.tar # Un-combine foo.tar into current directory 

df # List disks, size, used and available space df -h|--human-readable # List disks, size, used and available space in a human readable format du # List current directory, subdirectories and file sizes du /foo/bar # List specified directory, subdirectories and file sizes du -h|--human-readable # List current directory, subdirectories and file sizes in a human readable format du -d|--max-depth # List current directory, subdirectories and file sizes within the max depth du -d 0 # List current directory size 

free # Show memory usage free -h|--human # Show human readable memory usage free -h|--human --si # Show human readable memory usage in power of 1000 instead of 1024 free -s|--seconds 5 # Show memory usage and update continuously every five seconds 

apt update # Refreshes repository index apt search wget # Search for a package apt show wget # List information about the wget package apt list --all-versions wget # List all versions of the package apt install wget # Install the latest version of the wget package apt install wget=1.2.3 # Install a specific version of the wget package apt remove wget # Removes the wget package apt upgrade # Upgrades all upgradable packages 

shutdown # Shutdown in 1 minute shutdown now "Cya later" # Immediately shut down shutdown +5 "Cya later" # Shutdown in 5 minutes shutdown --reboot # Reboot in 1 minute shutdown -r now "Cya later" # Immediately reboot shutdown -r +5 "Cya later" # Reboot in 5 minutes shutdown -c # Cancel a shutdown or reboot reboot # Reboot now reboot -f # Force a reboot 

top # List all processes interactively htop # List all processes interactively ps all # List all processes pidof foo # Return the PID of all foo processes CTRL+Z # Suspend a process running in the foreground bg # Resume a suspended process and run in the background fg # Bring the last background process to the foreground fg 1 # Bring the background process with the PID to the foreground sleep 30 & # Sleep for 30 seconds and move the process into the background jobs # List all background jobs jobs -p # List all background jobs with their PID lsof # List all open files and the process using them lsof -itcp:4000 # Return the process listening on port 4000 

nice -n -20 foo # Change process priority by name renice 20 PID # Change process priority by PID ps -o ni PID # Return the process priority of PID 

CTRL+C # Kill a process running in the foreground kill PID # Shut down process by PID gracefully. Sends TERM signal. kill -9 PID # Force shut down of process by PID. Sends SIGKILL signal. pkill foo # Shut down process by name gracefully. Sends TERM signal. pkill -9 foo # force shut down process by name. Sends SIGKILL signal. killall foo # Kill all process with the specified name gracefully. 

date # Print the date and time date --iso-8601 # Print the ISO8601 date date --iso-8601=ns # Print the ISO8601 date and time time tree # Time how long the tree command takes to execute 

 * * * * * Minute, Hour, Day of month, Month, Day of the week 

crontab -l # List cron tab crontab -e # Edit cron tab in Vim crontab /path/crontab # Load cron tab from a file crontab -l > /path/crontab # Save cron tab to a file * * * * * foo # Run foo every minute */15 * * * * foo # Run foo every 15 minutes 0 * * * * foo # Run foo every hour 15 6 * * * foo # Run foo daily at 6:15 AM 44 4 * * 5 foo # Run foo every Friday at 4:44 AM 0 0 1 * * foo # Run foo at midnight on the first of the month 0 0 1 1 * foo # Run foo at midnight on the first of the year at -l # List scheduled tasks at -c 1 # Show task with ID 1 at -r 1 # Remove task with ID 1 at now + 2 minutes # Create a task in Vim to execute in 2 minutes at 12:34 PM next month # Create a task in Vim to execute at 12:34 PM next month at tomorrow # Create a task in Vim to execute tomorrow 

curl https://example.com # Return response body curl -i|--include https://example.com # Include status code and HTTP headers curl -L|--location https://example.com # Follow redirects curl -o|--remote-name foo.txt https://example.com # Output to a text file curl -H|--header "User-Agent: Foo" https://example.com # Add a HTTP header curl -X|--request POST -H "Content-Type: application/json" -d|--data '{"foo":"bar"}' https://example.com # POST JSON curl -X POST -H --data-urlencode foo="bar" http://example.com # POST URL Form Encoded wget https://example.com/file.txt . # Download a file to the current directory wget -O|--output-document foo.txt https://example.com/file.txt # Output to a file with the specified name 

ping example.com # Send multiple ping requests using the ICMP protocol ping -c 10 -i 5 example.com # Make 10 attempts, 5 seconds apart ip addr # List IP addresses on the system ip route show # Show IP addresses to router netstat -i|--interfaces # List all network interfaces and in/out usage netstat -l|--listening # List all open ports traceroute example.com # List all servers the network traffic goes through mtr -w|--report-wide example.com # Continually list all servers the network traffic goes through mtr -r|--report -w|--report-wide -c|--report-cycles 100 example.com # Output a report that lists network traffic 100 times nmap 0.0.0.0 # Scan for the 1000 most common open ports on localhost nmap 0.0.0.0 -p1-65535 # Scan for open ports on localhost between 1 and 65535 nmap 192.168.4.3 # Scan for the 1000 most common open ports on a remote IP address nmap -sP 192.168.1.1/24 # Discover all machines on the network by ping'ing them 

host example.com # Show the IPv4 and IPv6 addresses dig example.com # Show complete DNS information cat /etc/resolv.conf # resolv.conf lists nameservers 

lsusb # List USB devices lspci # List PCI hardware lshw # List all hardware 

tmux # Start a new session (CTRL-b + d to detach) tmux ls # List all sessions tmux attach -t 0 # Reattach to a session screen # Start a new session (CTRL-a + d to detach) screen -ls # List all sessions screen -R 31166 # Reattach to a session exit # Exit a session 

ssh hostname # Connect to hostname using your current user name over the default SSH port 22 ssh -i foo.pem hostname # Connect to hostname using the identity file ssh user@hostname # Connect to hostname using the user over the default SSH port 22 ssh user@hostname -p 8765 # Connect to hostname using the user over a custom port ssh ssh://user@hostname:8765 # Connect to hostname using the user over a custom port 

$ cat ~/.ssh/config Host name User foo Hostname 127.0.0.1 Port 8765 $ ssh name 

scp foo.txt ubuntu@hostname:/home/ubuntu # Copy foo.txt into the specified remote directory 

# Always run ls after cd function cd { builtin cd "$@" && ls } # Prompt user before overwriting any files alias cp='cp --interactive' alias mv='mv --interactive' alias rm='rm --interactive' # Always show disk usage in a human readable format alias df='df -h' alias du='du -h' 

#!/bin/bash foo=123 # Initialize variable foo with 123 declare -i foo=123 # Initialize an integer foo with 123 declare -r foo=123 # Initialize readonly variable foo with 123 echo $foo # Print variable foo echo ${foo}_'bar' # Print variable foo followed by _bar echo ${foo:-'default'} # Print variable foo if it exists otherwise print default export foo # Make foo available to child processes unset foo # Make foo unavailable to child processes 

#!/bin/bash env # List all environment variables echo $PATH # Print PATH environment variable export FOO=Bar # Set an environment variable 

#!/bin/bash greet() { local world = "World" echo "$1 $world" return "$1 $world" } greet "Hello" greeting=$(greet "Hello") 

#!/bin/bash exit 0 # Exit the script successfully exit 1 # Exit the script unsuccessfully echo $? # Print the last exit code 

#!/bin/bash if [[$foo = 'bar']]; then echo 'one' elif [[$foo = 'bar']] || [[$foo = 'baz']]; then echo 'two' elif [[$foo = 'ban']] && [[$USER = 'bat']]; then echo 'three' else echo 'four' fi 

#!/bin/bash [[ $USER = 'rehan' ]] && echo 'yes' || echo 'no' 

#!/bin/bash declare -i counter counter=10 while [$counter -gt 2]; do echo The counter is $counter counter=counter-1 done 

#!/bin/bash for i in {0..10..2} do echo "Index: $i" done for filename in file1 file2 file3 do echo "Content: " >> $filename done for filename in *; do echo "Content: " >> $filename done 

#!/bin/bash echo "What's the weather like tomorrow?" read weather case $weather in sunny | warm ) echo "Nice weather: " $weather ;; cloudy | cool ) echo "Not bad weather: " $weather ;; rainy | cold ) echo "Terrible weather: " $weather ;; * ) echo "Don't understand" ;; esac