Complete Bash (Bourne Again Shell) Cheatsheet

pwd

Print working directory - shows your current location in the filesystem

$ pwd
# Output: /home/user/documents

cd [directory]

Change directory - move to a different folder

cd /path/to/dir # Absolute path
cd .. # Move up one level
cd ~ # Home directory
cd - # Previous directory

ls [options] [directory]

List directory contents - view files and folders

ls -l # Long format with details
ls -a # Show hidden files
ls -lh # Human-readable file sizes
ls -t # Sort by modification time
ls -R # Recursive listing

touch filename

Create empty file or update file timestamp

touch file.txt
touch -t 202301010000 oldfile.txt # Set specific timestamp

cp [options] source destination

Copy files and directories

cp file1 file2
cp -r dir1 dir2 # Recursive copy
cp -i file* dir # Interactive (prompt before overwrite)
cp -v file.txt backup/ # Verbose output

mv [options] source destination

Move or rename files and directories

mv oldname newname
mv file1 file2 dir/
mv -n file.txt destination/ # No overwrite

rm [options] file

Remove files and directories (use with caution!)

rm file.txt
rm -r dir/ # Recursive remove
rm -f file # Force remove (no prompt)
rm -i file* # Interactive remove (prompt)

mkdir [options] directory

Create directories

mkdir newdir
mkdir -p path/to/newdir # Create parent directories as needed
mkdir -m 755 protected_dir # With specific permissions

chmod [options] permissions file

Change file permissions

chmod 755 script.sh
chmod +x executable # Add execute permission
chmod -R 644 dir/ # Recursive permission change
chmod u=rw,go=r file.txt # Symbolic permissions

chown [options] user:group file

Change file owner and group

chown user:group file.txt
chown -R www-data:www-data /var/www # Recursive ownership
chown root: /etc/passwd # Set root owner with default group

find [path] [options] [expression]

Search for files in directory hierarchy

find /home -name "*.txt"
find . -type f -size +1M # Files larger than 1MB
find /var/log -mtime -7 # Modified in last 7 days
find . -name "temp*" -exec rm {} \; # Find and delete

cat [options] file

Concatenate and display file contents

cat file.txt
cat file1 file2 > combined
cat -n file.txt # Show line numbers
cat -v nonprint.txt # Display non-printing characters

grep [options] pattern [file]

Search for patterns in files (Global Regular Expression Print)

grep "error" logfile.txt
grep -r "TODO" src/ # Recursive search
grep -i "warning" file.log # Case insensitive
grep -v "success" results.csv # Invert match
grep -E "[0-9]{3}-[0-9]{4}" contacts.txt # Extended regex

sed [options] 'command' file

Stream editor for filtering and transforming text

sed 's/old/new/g' file.txt # Replace text globally
sed -i.bak 's/foo/bar/' config.ini # In-place edit with backup
sed '/^#/d' script.sh # Delete comment lines
sed -n '5,10p' longfile.txt # Print lines 5-10

awk 'pattern {action}' file

Powerful text processing and data extraction

awk '{print $1}' file.txt # Print first column
awk -F',' '{print $2}' data.csv # CSV processing
awk '$3 > 100 {print $0}' data.txt # Filter rows
awk 'BEGIN {sum=0} {sum+=$1} END {print sum}' numbers.txt # Sum column

head [options] file

Display first part of files

head file.txt # First 10 lines
head -n 20 log.txt # First 20 lines
head -c 100 data.bin # First 100 bytes

tail [options] file

Display last part of files

tail file.log # Last 10 lines
tail -n 20 access.log # Last 20 lines
tail -f /var/log/syslog # Follow log in real-time

sort [options] file

Sort lines of text files

sort names.txt # Alphabetical sort
sort -n numbers.txt # Numerical sort
sort -r data.txt # Reverse sort
sort -u duplicates.txt # Unique sort

uniq [options] file

Report or omit repeated lines

uniq duplicates.txt # Remove consecutive duplicates
uniq -c log.txt # Count occurrences
uniq -d repeated.txt # Only show duplicates

wc [options] file

Word count

wc file.txt # Lines, words, characters
wc -l *.log # Count lines in each log file
wc -c binary.dat # Count bytes

uname [options]

Print system information

uname -a # All system info
uname -s # Kernel name
uname -r # Kernel release

df [options]

Disk space usage

df -h # Human-readable sizes
df -i # Inode usage
df -T /dev/sda1 # Filesystem type

du [options] [file]

Estimate file space usage

du -sh /home # Summary of directory size
du -ah --max-depth=1 # All files one level deep
du -BM /var/log # Sizes in megabytes

free [options]

Display memory usage

free -h # Human-readable output
free -m # Show in megabytes
free -s 5 # Continuous display every 5 seconds

top

Display Linux processes

top # Interactive process viewer
top -u apache # Show only apache processes
top -n 1 -b > processes.txt # Save snapshot

uptime

Show how long system has been running

uptime # Output: 14:30:45 up 3 days, 2:30, 3 users, load average: 0.15, 0.10, 0.05

ps [options]

Report a snapshot of current processes

ps aux # Show all processes
ps -ef # Full format listing
ps -u root # Processes by user
ps --forest # Show process hierarchy

kill [options] PID

Terminate processes by ID

kill 1234 # Terminate process 1234
kill -9 5678 # Force kill process
kill -l # List all signals

pkill [options] pattern

Kill processes by name

pkill firefox # Kill all firefox processes
pkill -u bob # Kill all processes owned by bob
pkill -f "python script.py" # Kill by full command

bg [job_spec]

Resume suspended jobs in background

bg %1 # Resume job 1 in background
bg # Resume current job

fg [job_spec]

Bring jobs to foreground

fg %2 # Bring job 2 to foreground
fg # Bring current job to foreground

ping [options] host

Send ICMP ECHO_REQUEST to network hosts

ping google.com # Continuous ping
ping -c 4 8.8.8.8 # Ping 4 times
ping -i 5 example.org # Ping every 5 seconds

ifconfig [interface]

Configure network interfaces (deprecated, use ip instead)

ifconfig # List all interfaces
ifconfig eth0 up # Bring interface up
ifconfig eth0 192.168.1.100 # Set IP address

netstat [options]

Print network connections, routing tables, interface statistics

netstat -tulnp # Listening ports
netstat -r # Routing table
netstat -s # Statistics by protocol

ssh [options] [user@]hostname

OpenSSH SSH client (remote login program)

ssh user@example.com # Basic login
ssh -p 2222 admin@server # Custom port
ssh -i ~/.ssh/key.pem ubuntu@aws-server # With identity file

#!/bin/bash

Shebang line to make file executable as bash script

#!/bin/bash
echo "Hello World"

Variables

Variable declaration and usage

name="John" # Assign value
echo $name # Access variable
readonly PI=3.14 # Read-only variable
unset name # Delete variable

Conditionals

If/else statements

if [ $age -gt 18 ]; then
  echo "Adult"
elif [ $age -gt 12 ]; then
  echo "Teen"
else
  echo "Child"
fi

Loops

For and while loops

# For loop
for i in {1..5}; do
  echo "Number: $i"
done

# While loop
count=1
while [ $count -le 5 ]; do
  echo "Count: $count"
  ((count++))
done

Functions

Define and call functions

greet() {
local name=$1
echo "Hello, $name"
}

greet "Alice" # Call function

Command-line arguments

Access script arguments

echo "Script name: $0"
echo "First arg: $1"
echo "All args: $@"
echo "Arg count: $#"
echo "Last exit status: $?"

Debugging

Debug bash scripts

bash -x script.sh # Trace execution
set -x # Enable debugging
set +x # Disable debugging
trap 'echo Error at line $LINENO' ERR # Error handling

Ctrl + A

Move cursor to beginning of line

Ctrl + E

Move cursor to end of line

Ctrl + U

Delete from cursor to beginning of line

Ctrl + K

Delete from cursor to end of line

Ctrl + W

Delete previous word

Ctrl + R

Search command history

Ctrl + C

Terminate current command

Ctrl + Z

Suspend current command (use fg to resume)

Ctrl + D

Exit shell (when on empty line)

Tab

Auto-complete file or command

!!

Repeat last command

!command

Run most recent command starting with 'command'

Complete Bash Cheatsheet

Quick Reference

Table of Contents

1 Navigation

2 File Operations

3 Text Processing

4 System Information

5 Processes

6 Networking

7 Scripting

8 Keyboard Shortcuts