Bash Scripting Cheat Sheet 2026: Syntax and Examples

A quick reference for Bash — the most common shell for Linux administration. Bookmark this page.

Navigation and Files

# Navigate
cd /path/to/dir
cd -           # Previous directory
cd ~           # Home directory
pwd            # Print working directory

# List files
ls -la         # Long format, all files
ls -lh         # Human-readable sizes
ls -lt         # Sort by modification time
ls -lS         # Sort by size

# File operations
cp source dest
cp -r dir/ dest/           # Copy directory recursively
mv old new                 # Move/rename
rm file                    # Delete file
rm -rf dir/                # Delete directory (careful!)
mkdir -p path/to/dir       # Create nested directories

Text Processing

# Search
grep "pattern" file
grep -r "pattern" dir/      # Recursive search
grep -i "pattern" file      # Case insensitive
grep -n "pattern" file      # Show line numbers
grep -v "pattern" file      # Invert match (exclude)

# Process text
cat file | head -20         # First 20 lines
cat file | tail -20         # Last 20 lines
tail -f /var/log/syslog     # Follow log in real-time
wc -l file                  # Count lines
sort file | uniq -c | sort -rn  # Count unique occurrences

# Find and replace
sed 's/old/new/g' file           # Replace all occurrences
sed -i 's/old/new/g' file       # In-place replace
awk '{print $1, $3}' file       # Print columns 1 and 3
awk -F: '{print $1}' /etc/passwd # Use custom delimiter

Variables and Control Flow

# Variables
NAME="world"
echo "Hello, $NAME"
echo "Path: ${HOME}/bin"

# Command substitution
DATE=$(date +%Y-%m-%d)
FILE_COUNT=$(ls | wc -l)

# Conditionals
if [ -f "/path/to/file" ]; then
    echo "File exists"
elif [ -d "/path/to/dir" ]; then
    echo "Directory exists"
else
    echo "Not found"
fi

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

for i in {1..10}; do
    echo "Iteration $i"
done

while read -r line; do
    echo "$line"
done < input.txt

Process Management

# View processes
ps aux                      # All processes
ps aux | grep nginx         # Filter
top                         # Interactive process viewer
htop                        # Better interactive viewer

# Background jobs
command &                   # Run in background
jobs                        # List background jobs
fg %1                       # Bring job 1 to foreground
bg %1                       # Resume job 1 in background
nohup command &             # Survive terminal close

# Kill processes
kill PID                    # Send SIGTERM
kill -9 PID                 # Force kill (SIGKILL)
pkill -f "process name"     # Kill by name pattern

Disk and Network

# Disk
df -h                       # Disk space
du -sh dir/                 # Directory size
du -sh * | sort -rh | head  # Largest items in current dir

# Network
curl -s https://api.example.com | jq .
wget -q https://example.com/file.zip
ss -tlnp                    # Open listening ports
ip addr show                # IP addresses
ping -c 4 example.com       # Connectivity test

Permissions

# Change permissions
chmod 755 script.sh         # rwxr-xr-x
chmod +x script.sh          # Add execute
chmod -R 644 dir/           # Recursive

# Change ownership
chown user:group file
chown -R user:group dir/

Tips and Tricks

• Use !! to repeat the last command: sudo !!
• Use ctrl+r for reverse history search
• Use set -euo pipefail at the top of scripts for safety
• Use xargs to parallelize: find . -name "*.log" | xargs -P4 gzip
• Use trap for cleanup: trap 'rm -f /tmp/lockfile' EXIT

Related Resources

• Linux Cheat Sheet
• Vim Cheat Sheet
• Git Cheat Sheet