Linux & Bash Cheat Sheet: Commands Every Dev Needs

Quick reference tables

Navigation

| Command | What it does | |---|---| | pwd | Print current directory | | ls | List files | | ls -la | List all files with details (including hidden) | | ls -lh | Human-readable file sizes | | cd /path | Change to absolute path | | cd ~ | Go to home directory | | cd - | Go to previous directory | | cd .. | Go up one level | | tree | Show directory tree | | tree -L 2 | Tree limited to 2 levels deep |

File operations

| Command | What it does | |---|---| | touch file.txt | Create an empty file | | mkdir dir | Create a directory | | mkdir -p a/b/c | Create nested directories | | cp file dest | Copy file | | cp -r dir dest | Copy directory recursively | | mv file dest | Move or rename file | | rm file | Remove a file | | rm -r dir | Remove directory recursively | | rm -rf dir | Force remove (no prompts — careful!) | | ln -s target link | Create a symbolic link |

Reading files

| Command | What it does | |---|---| | cat file | Print entire file | | less file | Scroll through file (q to quit) | | head file | First 10 lines | | head -n 20 file | First 20 lines | | tail file | Last 10 lines | | tail -n 20 file | Last 20 lines | | tail -f file | Follow file in real time (logs) | | wc -l file | Count lines | | wc -w file | Count words |

Searching — grep & find

| Command | What it does | |---|---| | grep "pattern" file | Search for pattern in file | | grep -r "pattern" dir | Search recursively in directory | | grep -i "pattern" file | Case-insensitive search | | grep -n "pattern" file | Show line numbers | | grep -v "pattern" file | Invert — lines that don’t match | | grep -l "pattern" dir/* | List files containing pattern | | find . -name "*.js" | Find files by name pattern | | find . -type f -name "*.log" | Find files only (not dirs) | | find . -type d -name "node_modules" | Find directories by name | | find . -mtime -7 | Files modified in last 7 days | | find . -size +10M | Files larger than 10MB |

Permissions

| Command | What it does | |---|---| | ls -l | Show permissions in listing | | chmod 755 file | Set permissions (rwxr-xr-x) | | chmod +x file | Make file executable | | chmod -R 755 dir | Set permissions recursively | | chown user file | Change file owner | | chown user:group file | Change owner and group | | chown -R user:group dir | Change ownership recursively | | sudo command | Run as superuser | | su - user | Switch to another user |

Permission numbers:

| Number | Permissions | |---|---| | 7 | rwx (read + write + execute) | | 6 | rw- (read + write) | | 5 | r-x (read + execute) | | 4 | r— (read only) | | 0 | --- (no permissions) |

Processes

| Command | What it does | |---|---| | ps aux | List all running processes | | ps aux \| grep node | Find a specific process | | top | Live process monitor | | htop | Better live process monitor | | kill PID | Kill a process by ID | | kill -9 PID | Force kill | | killall node | Kill all processes named node | | pkill -f "pattern" | Kill processes matching pattern | | bg | Resume stopped job in background | | fg | Bring background job to foreground | | jobs | List background jobs | | nohup cmd & | Run command immune to hangup |

Disk & memory

| Command | What it does | |---|---| | df -h | Disk space usage (human-readable) | | du -sh dir | Size of a directory | | du -sh * | Size of each item in current dir | | free -h | RAM usage | | lsblk | List block devices (disks) |

Networking

| Command | What it does | |---|---| | ip a | Show IP addresses | | ip r | Show routing table | | ping host | Ping a host | | curl url | Fetch a URL | | curl -I url | Show HTTP headers only | | curl -o file url | Download to a file | | wget url | Download a file | | ss -tulnp | Show listening ports | | netstat -tulnp | Show listening ports (older) | | ssh user@host | SSH into a remote machine | | scp file user@host:/path | Copy file to remote | | rsync -avz src/ dest/ | Sync directories |

Archives & compression

| Command | What it does | |---|---| | tar -czf archive.tar.gz dir/ | Create gzipped tar archive | | tar -xzf archive.tar.gz | Extract gzipped tar | | tar -tzf archive.tar.gz | List contents without extracting | | zip -r archive.zip dir/ | Create zip archive | | unzip archive.zip | Extract zip | | gzip file | Compress a file (replaces original) | | gunzip file.gz | Decompress |

Pipes, redirects & shortcuts

| Symbol | What it does | |---|---| | cmd1 \| cmd2 | Pipe output of cmd1 to cmd2 | | > file | Redirect stdout to file (overwrite) | | >> file | Redirect stdout to file (append) | | 2> file | Redirect stderr to file | | 2>&1 | Redirect stderr to stdout | | &> file | Redirect both stdout and stderr | | /dev/null | Discard output | | < file | Read stdin from file | | cmd & | Run command in background |

Shell keyboard shortcuts

| Shortcut | What it does | |---|---| | Ctrl+C | Kill current process | | Ctrl+Z | Suspend current process | | Ctrl+D | Exit shell / EOF | | Ctrl+L | Clear screen | | Ctrl+A | Jump to start of line | | Ctrl+E | Jump to end of line | | Ctrl+U | Delete from cursor to start of line | | Ctrl+K | Delete from cursor to end of line | | Ctrl+W | Delete word before cursor | | Ctrl+R | Search command history | | ↑ / ↓ | Navigate command history | | !! | Repeat last command | | !$ | Last argument of previous command | | !cmd | Run most recent command starting with cmd |

Variables & environment

| Command | What it does | |---|---| | VAR=value | Set a local variable | | export VAR=value | Set an environment variable | | echo $VAR | Print a variable | | env | Show all environment variables | | unset VAR | Remove a variable | | printenv PATH | Print a specific env variable | | source ~/.bashrc | Reload shell config | | which cmd | Show path to a command | | type cmd | Show how a command is interpreted |

Detailed sections

Pipes — the real power of the terminal

Pipes (|) connect commands so the output of one becomes the input of the next.

# Find all .js files and count them
find . -name "*.js" | wc -l

# See the 10 largest files
du -sh * | sort -rh | head -10

# Search running processes for 'node' and kill them
ps aux | grep node | awk '{print $2}' | xargs kill

# See only unique lines in a file
cat file.txt | sort | uniq

# Count occurrences of each word
cat file.txt | tr ' ' '\n' | sort | uniq -c | sort -rn | head -20

Grep — search like a pro

# Search recursively, show filename and line number
grep -rn "TODO" ./src

# Search for multiple patterns
grep -E "error|warning|critical" app.log

# Show context around matches (3 lines before and after)
grep -C 3 "error" app.log

# Count matches per file
grep -rc "TODO" ./src

# Exclude a directory
grep -r "pattern" . --exclude-dir=node_modules

Find — locate files quickly

# Find and delete all .DS_Store files
find . -name ".DS_Store" -delete

# Find files modified in the last 24 hours
find . -mtime -1 -type f

# Find files larger than 100MB
find . -size +100M -type f

# Execute a command on each result
find . -name "*.log" -exec rm {} \;

# Find empty directories
find . -type d -empty

Cron — scheduled tasks

Edit the crontab:

crontab -e

Format: minute hour day-of-month month day-of-week command

# Every minute
* * * * * /path/to/script.sh

# Every day at midnight
0 0 * * * /path/to/script.sh

# Every Monday at 9am
0 9 * * 1 /path/to/script.sh

# Every 15 minutes
*/15 * * * * /path/to/script.sh

# First day of every month at noon
0 12 1 * * /path/to/script.sh

List cron jobs: crontab -l Remove all cron jobs: crontab -r

SSH essentials

# Connect to a server
ssh user@192.168.1.10

# Connect on a non-standard port
ssh -p 2222 user@host

# Copy a file to a server
scp localfile.txt user@host:/remote/path/

# Copy a directory to a server
scp -r localdir/ user@host:/remote/path/

# Generate an SSH key pair
ssh-keygen -t ed25519 -C "your@email.com"

# Copy your public key to a server (enables passwordless login)
ssh-copy-id user@host

# SSH tunnel (forward remote port 5432 to localhost)
ssh -L 5432:localhost:5432 user@host

Writing shell scripts

#!/bin/bash
set -e    # exit on any error
set -u    # error on undefined variables

# Variables
NAME="world"
echo "Hello, $NAME!"

# Conditionals
if [ -f "file.txt" ]; then
  echo "File exists"
else
  echo "File not found"
fi

# Loops
for file in *.js; do
  echo "Processing $file"
done

# Functions
greet() {
  echo "Hello, $1!"
}
greet "developer"

# Command substitution
DATE=$(date +%Y-%m-%d)
echo "Today is $DATE"

Make it executable: chmod +x script.sh Run it: ./script.sh

Related: Vim Cheat Sheet | tmux Cheat Sheet | SSH & GPG Cheat Sheet | cURL Cheat Sheet

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