Bash Cheatsheet : Guide to Boost Your Terminal Productivity

Moving and Navigating:

CTRL+A: Moves the cursor to the beginning of the current line.
CTRL+B: Shifts the cursor one character backward.
CTRL+C: Interrupts the current command’s execution.
CTRL+D: Removes the character before the cursor or logs out of the session (like “exit”).
CTRL+E: Moves the cursor to the end of the current line.
CTRL+F: Advances the cursor one character forward.
CTRL+G: Aborts the current editing action and triggers a terminal bell.
CTRL+H: Deletes the character under the cursor (similar to DELETE).
CTRL+J: Performs the same action as pressing RETURN/Enter.
CTRL+K: Deletes (kills) text from the cursor to the end of the line.
CTRL+L: Clears the screen and displays the current line.
CTRL+M: Functions like pressing RETURN/Enter.
CTRL+N: Moves to the next line in command history.
CTRL+O: Performs the same action as RETURN/Enter and displays the next line from history.
CTRL+P: Moves to the previous line in command history.
CTRL+Q: Resumes suspended shell output.
CTRL+R: Searches backward in command history.
CTRL+S: Searches forward or suspends shell output.
CTRL+T: Swaps the positions of two characters.
CTRL+U: Deletes (kills) text backward from the cursor to the beginning of the line.
CTRL+V: Inserts the next character typed verbatim.
CTRL+W: Deletes (kills) the word before the cursor.
CTRL+X: Lists possible filename completions for the current word.
CTRL+Y: Yanks (retrieves) the most recently killed item.
CTRL+Z: Stops the current command and can be resumed with fg (foreground) or bg (background).

ALT Key Combinations:

ALT+B: Moves the cursor backward one word.
ALT+D: Deletes the next word.
ALT+F: Advances the cursor forward one word.
ALT+H: Deletes the character before the cursor.
ALT+T: Swaps the positions of two words.
ALT+.: Pastes the last word from the previous command, cycling through command history.
ALT+U: Capitalizes every character from the cursor to the end of the word.
ALT+L: Converts every character from the cursor to the end of the word to lowercase.
ALT+C: Capitalizes the character under the cursor and moves to the word’s end.
ALT+R: Reverts changes to a command from history if edited.
ALT+?: Lists possible completions for the current input.
ALT+^: Expands the line to the most recent match from history.

Keyboard Macros and Editing:

CTRL+X ( ): Starts and stops recording a keyboard macro.
CTRL+X E: Recalls the last recorded keyboard macro.
CTRL+X CTRL+E: Invokes the text editor specified by $EDITOR on the current command line and executes the result as shell commands.
CTRL+A D: Logs out from the screen without terminating any existing commands.

Deleting and Exiting:

BACKSPACE: Deletes the character before the cursor.
DELETE: Deletes the character under the cursor.

Command History and Repeating:

history: Displays the command line history.
!!: Repeats the last command.
!<n>: Refers to the command line with index ‘n’.
!<string>: Refers to the command starting with ‘string’.

Exiting:

esc :wq: Exits the text editor and saves changes.
exit: Logs out of the current session.

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Display Environment Variables:
- View all the environment variables set in your shell session using the command env.
Check Shell and Version:
- Identify the current shell being used with echo $SHELL.
- Determine the version of Bash in use by running echo $BASH_VERSION.
Switch to Bash or Return:
- Change your shell to Bash temporarily by typing bash (exit using exit).
- Locate the binary, source, and manual-page of a command using whereis bash.
- Find the program executed as ‘bash’ with which bash.
Clear the Terminal:
- Clear the contents displayed on the terminal screen using the clear command.
List Files and Directories:
- List files in the current directory using ls, or specify a directory with ls <dir>.
- Display detailed information, including permissions and ownership, with ls -l.
- List all files, including hidden ones, using ls -a.
Symbolic Links and File Trees:
- Create a symbolic link to a file with ln -s <filename> <link>.
- View the target of a symbolic link using readlink <filename>.
- Display the directory structure in a readable tree format with tree.
File Operations and Exploration:
- Use the Midnight Commander file explorer in the terminal with mc.
- Create or update a file using touch <filename>.
- Generate temporary files or directories using mktemp -t <filename>.
File Content Manipulation:
- Display the raw content of a file using cat <filename>.
- Add line numbers to the content with cat -n <filename>.
- Show the number of lines in a file using nl <file.sh>.
File Merging and Redirection:
- Copy the content of filename1 to filename2 using cat filename1 > filename2.
- Append the content of filename1 to filename2 with cat filename1 >> filename2.
- Redirect the standard output of a command to a file using any_command > <filename>.
Paging and Viewing Files:
- Display the beginning of a file using more <filename> (scroll with space, quit with q).
- Output the first lines of a file with head <filename> (default: 10 lines).
- View the last lines of a file using tail <filename> (use -f for real-time updates).
Text Editing and Manipulation:
- Open and edit a file using the VIM text editor with vim <filename>.
File and Directory Management:
- Move a file to a specified destination with mv <filename1> <dest>.
- Copy a file to a destination using cp <filename1> <dest>.
- Remove a file using rm <filename>.
File Searching and Comparison:
- Search for files or directories by name using find . -name <name> <type>.
- Compare two files and display differences with diff <filename1> <filename2>.
File Size and Sorting:
- Determine the line, word, and character count of a file with wc <filename>.
- Sort the lines of a text file alphabetically using sort <filename> (add -n for numeric, -r for reverse).
- Sort based on a specific field using sort -t -k <filename>.
String Manipulation and Permissions:
- Reverse the characters of a string using rev.
- Modify file permissions using chmod -options <filename>.
File Compression and Printing:
- Compress files using the gzip algorithm with gzip <filename>.
- Decompress gzip-compressed files with gunzip <filename>.
- View the contents of a gzipped file without decompressing using gzcat <filename>.
- Print a file using lpr <filename>.
- Check the printer queue status with lpq.
- Remove a job from the printer queue using lprm <jobnumber>.
File Conversion and Text Search:
- Convert plain text files into postscript format with genscript.
- Print .dvi files produced by LaTeX using dvips <filename>.
- Search for a specific pattern in files using grep <pattern> <filenames> or recursively in a directory with grep -r <pattern> <dir>.
Extracting Lines and Replacing Text:
- Extract and display a range of lines from a file using head -n file_name | tail +n or head -y lines.txt | tail +x.
- Replace a pattern with a replacement value in a file using sed 's/<pattern>/<replacement>/g' <filename>, or in-place using sed -i 's/<pattern>/<replacement>/g' <filename>.
- Replace a pattern from input using echo "this" | sed 's/is/at/g'.

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Directory Commands

Create a new directory: mkdir <dirname>
Remove an empty directory: rmdir <dirname>
Remove a non-empty directory and its contents forcefully: rmdir -rf <dirname>
Rename a directory from <dir1> to <dir2>: mv <dir1> <dir2>
Change to the home directory: cd
Change to the parent directory: cd ..
Change to a specific directory: cd <dirname>
Copy <dir1> and its contents, including sub-directories, into <dir2>: cp -r <dir1> <dir2>
Display the current working directory: pwd
Change to the home directory: cd ~
Change to the previous working directory: cd -

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SSH, System Info & Network Commands

SSH:
- Connect to host as user: ssh user@host
- Connect to host on specific port: ssh -p <port> user@host
- Add SSH key to host: ssh-copy-id user@host
System Info:
- Display username: whoami
- Switch user: su <user>
- Switch to root (use sudo su -): su -
- Execute command as root: sudo <command>
- Change password: passwd
- Show disk quota: quota -v
- Display date and time: date
- Show calendar: cal
- View uptime: uptime
- Show online users: w
- Display user info: finger <user>
- Kernel info: uname -a
- Command manual: man <command>
- Alternative documentation: info <command>
- Built-in command help: help
Disk and File:
- Show disk usage: df
- Show file/dir disk usage: du <filename>
- Resize file system: resize2fs
Process Management:
- Show last logins: last <yourUsername>
- List user processes: ps -u yourusername
- Kill process by PID: kill <PID>
- Kill processes by name: killall <processname>
- Display active processes: top
- List open files: lsof
- Manage jobs:
  - List stopped jobs: bg
  - Bring job to foreground: fg
  - Bring specific job to foreground: fg <job>
Network:
- Ping host: ping <host>
- WHOIS lookup: whois <domain>
- DNS info: dig <domain>
- Reverse lookup: dig -x <host>
- Download file: wget <file>
- Network stats: netstat
- Measure command time: time <command>

Note: Be cautious when using commands that involve system changes or root access.

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Variables:

varname=value: Defines a variable.
varname=value command: Defines a variable for a subprocess.
echo $varname: Checks variable value.
echo $$: Prints process ID of current shell.
echo $!: Prints ID of recent background job.
echo $?: Displays exit status of last command.
read varname: Reads input into a variable.
read -p "prompt" varname: Reads input with a prompt.
let varname = equation: Performs math calculation.
export VARNAME=value: Defines an environment variable.
export -f funcname: Exports function ‘funcname’.
export var1="var1 value": Export and assign.
export varname: Copies Bash variable.
declare -x varname: Copies Bash variable.
${!varprefix*}: Expands to names of variables with specified prefix.
${!varprefix@}: Expands to names of variables with specified prefix (array-like syntax).
declare -p varname: Display the attributes and value of a variable.
typeset -p varname: Same as declare, for compatibility with ksh.

Arrays:

array[0]=valA: Defines an array.
array[1]=valB
array[2]=valC
array=([2]=valC [0]=valA [1]=valB): Another way.
array=(valA valB valC): Yet another.
${array[i]}: Displays array value for index.
${#array[i]}: Length of array element.
${#array[@]}: Number of values in array.
declare -a: Treat variables as arrays.
declare -f: Functions only.
declare -F: Function names without defs.
declare -i: Treat variables as integers.
declare -r: Read-only variables.
declare -x: Mark variables for export.
declare -l: Convert to lowercase.
declare -A: Associative array.
array+=('new_element'): Add a new element to the end of the array.
unset array[index]: Remove an element from the array.
${#array[@]}: Number of elements in the array.
${array[*]} or ${array[@]}: Expands to all elements of the array.
${!array[@]}: Expands to indices of the array.
array[@]:slice_start:slice_length}: Extract a slice from the array.
array[*]:slice_start:slice_length}: Extract a slice from the array (all elements).

Substitution:

${varname:-word}: Return var or word.
${varname:word}: Return var or word.
${varname:=word}: Return var or set word.
${varname:?message}: Return var or error.
${varname:+word}: Return word if var.
${varname:offset:length}: Substring of var.

Pattern Matching:

${variable#pattern}: Delete short match.
${variable##pattern}: Delete long match.
${variable%pattern}: Delete short end match.
${variable%%pattern}: Delete long end match.
${variable/pattern/string}: Replace first match.
${variable//pattern/string}: Replace all matches.
${variable/pattern/string}: Replace first match of pattern with string.
${variable//pattern/string}: Replace all matches of pattern with string.
${variable/#pattern/string}: If pattern matches the beginning of variable, replace with string.
${variable/%pattern/string}: If pattern matches the end of variable, replace with string.

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Functions:

function funcname(): Define function.
unset -f funcname: Delete function.
declare -f: List defined functions.

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Flow Control:

&&: and operator.
||: or operator.
-a: and in test conditional.
-o: or in test conditional.

File and Directory Tests:

-a file: File exists or compiles.
-d file: File exists and is directory.
-e file: File exists.
-f file: File is regular.
-r file: Read permission.
-s file: File exists and not empty.
-w file: Write permission.
-x file: Execute permission.
-N file: Modified since last read.
-O file: You own file.
-G file: Group ID matches yours.
file1 -nt file2: file1 newer than file2.
file1 -ot file2: file1 older than file2.

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Looping:

for x in {1..10}: Loop with range.
for name [in list]: Loop through list.
for (( init; cond; update )): Numeric loop.
case expr in pattern): Case statement.
select name [in list]: Menu select.
while condition; do: While loop.
until condition; do: Until loop.

Input/Output:

cmd1|cmd2: Pipe output.
< file: Input from file.
> file: Output to file.
>> file: Append to file.
|tee <file>: Terminal and file output.

Process Handling:

myCommand &: Run job in background.
jobs: List all jobs.
fg: Bring job to foreground.
kill PID: Terminate process.
trap cmd sig1 sig2: Trap signals.
disown <PID|JID>: Remove job.
wait: Wait for jobs.
sleep <number>: Wait seconds.

Debugging:

bash -n scriptname: Syntax check.
bash -v scriptname: Echo before.
bash -x scriptname: Echo after.
trap cmd ERR: Trap errors.
trap cmd DEBUG: Trap debug.
trap cmd RETURN: Trap return.

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COLORS AND BACKGROUNDS

Reset: Color_Off=’\033[0m’
Regular Colors:
- Black: Black=’\033[0;30m’
- Red: Red=’\033[0;31m’
- Green: Green=’\033[0;32m’
- Yellow: Yellow=’\033[0;33m’
- Blue: Blue=’\033[0;34m’
- Purple: Purple=’\033[0;35m’
- Cyan: Cyan=’\033[0;36m’
- White: White=’\033[0;97m’
Additional Colors:
- Light Gray: LGrey=’\033[0;37m’
- Dark Gray: DGrey=’\033[0;90m’
- Light Red: LRed=’\033[0;91m’
- Light Green: LGreen=’\033[0;92m’
- Light Yellow: LYellow=’\033[0;93m’
- Light Blue: LBlue=’\033[0;94m’
- Light Purple: LPurple=’\033[0;95m’
- Light Cyan: LCyan=’\033[0;96m’
Bold:
- Black: BBlack=’\033[1;30m’
- Red: BRed=’\033[1;31m’
- Green: BGreen=’\033[1;32m’
- Yellow: BYellow=’\033[1;33m’
- Blue: BBlue=’\033[1;34m’
- Purple: BPurple=’\033[1;35m’
- Cyan: BCyan=’\033[1;36m’
- White: BWhite=’\033[1;37m’
Underline:
- Black: UBlack=’\033[4;30m’
- Red: URed=’\033[4;31m’
- Green: UGreen=’\033[4;32m’
- Yellow: UYellow=’\033[4;33m’
- Blue: UBlue=’\033[4;34m’
- Purple: UPurple=’\033[4;35m’
- Cyan: UCyan=’\033[4;36m’
- White: UWhite=’\033[4;37m’
Background:
- Black: On_Black=’\033[40m’
- Red: On_Red=’\033[41m’
- Green: On_Green=’\033[42m’
- Yellow: On_Yellow=’\033[43m’
- Blue: On_Blue=’\033[44m’
- Purple: On_Purple=’\033[45m’
- Cyan: On_Cyan=’\033[46m’
- White: On_White=’\033[47m’

Example of usage:

Use the color variables to change text color and background in Bash scripts.
Example:
- echo -e “${Green}This is GREEN text${Color_Off} and normal text”
- echo -e “${Red}${On_White}This is Red text on White background${Color_Off}”
- printf “${Red} This is red \n” (option -e is mandatory, it enables interpretation of backslash escapes)

Bash Cheatsheet : Guide to Boost Your Terminal Productivity

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