Forgetful Notes

Bash Cheat Sheet

This cheat sheet provides a quick reference for common Bash commands and scripting constructs.

Basic File and Directory Commands

ls          # List files and directories
ls -al      # List in long format, including hidden files
 
cd <dir>    # Change directory
cd ..       # Go up one directory
cd ~        # Go to home directory
 
pwd         # Print working directory
 
mkdir <dir> # Create a new directory
 
cp <src> <dest>   # Copy a file
cp -r <src> <dest>  # Copy a directory recursively
 
mv <src> <dest>   # Move or rename a file/directory
 
rm <file>   # Remove a file
rm -r <dir> # Remove a directory recursively
rm -rf <dir># Force remove without prompting (use with caution)
 
touch <file># Create an empty file or update its timestamp

Variables and Scripting

#!/bin/bash
 
# Variable assignment (no spaces around =)
NAME="World"
 
# Using a variable
echo "Hello, $NAME"
 
# Read user input
echo "Enter your name:"
read USER_INPUT
echo "Hello, $USER_INPUT"

Control Flow

If Statement

if [ "$NAME" == "World" ]; then
    echo "It is World."
elif [ -f "file.txt" ]; then
    echo "file.txt exists."
else
    echo "Condition not met."
fi

For Loop

for i in {1..5}; do
    echo "Number: $i"
done
 
for file in *; do
    echo "File: $file"
done

Command Chaining and Redirection

  • &&: Run next command only if the previous one succeeds.
  • ||: Run next command only if the previous one fails.
  • |: Pipe the output of one command to the input of another.
# Chaining
mkdir temp && cd temp
 
# Piping
ls -l | grep ".txt"
 
# Redirection
ls > file_list.txt      # Write output to file (overwrite)
ls >> file_list.txt     # Append output to file
ls > /dev/null          # Discard output
command 2> error.log    # Redirect stderr to a file
command &> output.log   # Redirect stdout and stderr

Searching and Finding

  • grep: Search for patterns in text.
  • find: Search for files and directories.
# Find text in a file (case-sensitive)
grep "error" log.txt
 
# Find text recursively in a directory, ignoring case
grep -ri "error" ./logs
 
# Find all files named "config.json" in the current directory
find . -name "config.json"
 
# Find all directories
find . -type d

Shell Shortcuts

  • Ctrl + C: Kill the current process.
  • Ctrl + R: Reverse search through command history.
  • Ctrl + A: Move cursor to the beginning of the line.
  • Ctrl + E: Move cursor to the end of the line.
  • !!: Execute the last command.

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