Unix CLI Cheat Sheet

Portable commands for Linux, macOS, and other Unix-like systems.

File Navigation

Command	Description
pwd	Print working directory
cd -	Go to previous directory
cd ~	Go to home directory
ls -la	List all files with details
ls -lah	Human-readable sizes
ls -lt	Sort by modification time
tree -L 2	Directory tree, 2 levels deep

File Operations

Command	Description
cp -r src dest	Copy directory recursively
mv old new	Move/rename
rm -rf dir	Remove directory recursively
mkdir -p a/b/c	Create nested directories
touch file	Create file or update timestamp
ln -s target link	Create symbolic link
stat file	File details
file filename	Detect file type

File Viewing

Command	Description
cat file	Print entire file
less file	Paginated view (q to quit)
head -n 20 file	First 20 lines
tail -n 20 file	Last 20 lines
tail -f file	Follow file (live updates)
wc -l file	Line count
diff file1 file2	Compare files
colordiff	Colored diff

Searching

Command	Description
find . -name "*.js"	Find by name
find . -type f -mtime -1	Files modified in last day
find . -size +100M	Files larger than 100MB
grep -r "pattern" .	Recursive search
grep -rn "pattern" .	With line numbers
grep -rl "pattern" .	List matching files only
grep -i "pattern"	Case insensitive
grep -v "pattern"	Invert match
rg "pattern"	Ripgrep (faster)
rg -t js "pattern"	Ripgrep, JS files only
fd "pattern"	Faster find alternative

Text Processing

Command	Description
sort file	Sort lines
sort -u file	Sort unique
sort -n file	Numeric sort
uniq	Remove adjacent duplicates
uniq -c	Count occurrences
cut -d',' -f1,3	Extract columns 1 and 3
awk '{print $1}'	Print first column
awk -F: '{print $1}'	Custom delimiter
sed 's/old/new/g'	Replace all occurrences
tr 'a-z' 'A-Z'	Translate characters
xargs	Build commands from stdin

sed In-Place Edit

# Linux
sed -i 's/old/new/g' file

# macOS (requires empty string for backup)
sed -i '' 's/old/new/g' file

Pipes & Redirection

Command	Description
cmd > file	Redirect stdout to file
cmd >> file	Append stdout to file
cmd 2> file	Redirect stderr
cmd &> file	Redirect both
cmd1 | cmd2	Pipe stdout to next command
cmd1 | tee file | cmd2	Pipe and save copy
cmd < file	Use file as stdin
cmd <<< "string"	Here string

Process Management

Command	Description
ps aux	All processes
ps aux | grep name	Find process
pgrep -f pattern	Get PIDs by pattern
top	Interactive process viewer
htop	Better process viewer
kill PID	Terminate process
kill -9 PID	Force kill
pkill -f pattern	Kill by pattern
killall name	Kill by name
jobs	List background jobs
bg	Resume job in background
fg	Bring job to foreground
nohup cmd &	Run immune to hangups
cmd &	Run in background
Ctrl+Z	Suspend current process
Ctrl+C	Interrupt process

Disk & Space

Command	Description
df -h	Disk free space
du -sh *	Directory sizes
du -sh * | sort -h	Sorted by size
ncdu	Interactive disk usage

Network

Command	Description
curl -I url	Headers only
curl -o file url	Download to file
curl -X POST -d "data" url	POST request
curl -H "Header: value" url	Custom header
wget url	Download file
ping host	Test connectivity
traceroute host	Trace route
netstat -an	Network connections
lsof -i :8080	What’s on port 8080
ss -tuln	Listening ports (Linux)
dig domain	DNS lookup
nslookup domain	DNS lookup
host domain	DNS lookup

Permissions

Command	Description
chmod 755 file	rwxr-xr-x
chmod +x file	Add execute permission
chmod -R 644 dir	Recursive
chown user:group file	Change owner
chown -R user dir	Recursive

Permission Numbers

Number	Permission
7	rwx (read, write, execute)
6	rw- (read, write)
5	r-x (read, execute)
4	r— (read only)
0	--- (none)

Common: 755 (dirs), 644 (files), 600 (private), 777 (all access)

Archive & Compression

Command	Description
tar -czvf archive.tar.gz dir	Create gzipped tarball
tar -xzvf archive.tar.gz	Extract gzipped tarball
tar -tf archive.tar	List contents
zip -r archive.zip dir	Create zip
unzip archive.zip	Extract zip
gzip file	Compress (replaces file)
gunzip file.gz	Decompress

Environment & Shell

Command	Description
env	Show environment variables
echo $VAR	Print variable
export VAR=value	Set variable
which cmd	Path to command
type cmd	Command type/location
alias ll='ls -la'	Create alias
source ~/.bashrc	Reload config
history	Command history
!!	Repeat last command
!$	Last argument of previous cmd
Ctrl+R	Reverse search history

SSH & Remote

Command	Description
ssh user@host	Connect
ssh -i key.pem user@host	With key file
ssh -L 8080:localhost:80 host	Local port forward
ssh -R 8080:localhost:80 host	Remote port forward
scp file user@host:path	Copy to remote
scp user@host:path file	Copy from remote
rsync -avz src dest	Sync directories
rsync -avz --delete src dest	Sync with delete

Useful Patterns

# Find and delete
find . -name "*.tmp" -delete

# Find and execute
find . -name "*.js" -exec wc -l {} +

# Count files by extension
find . -type f | sed 's/.*\.//' | sort | uniq -c | sort -rn

# Watch command output (Linux)
watch -n 2 'command'

# Parallel execution
cat urls.txt | xargs -P 4 -I {} curl {}

# JSON pretty print
cat file.json | python -m json.tool
cat file.json | jq '.'

# Get external IP
curl -s ifconfig.me

# Quick HTTP server
python -m http.server 8000

# Base64 encode/decode
echo "text" | base64
echo "dGV4dAo=" | base64 -d

# Generate random string
openssl rand -hex 16

# Monitor file changes
tail -f log.txt | grep --line-buffered "error"

# Process substitution
diff <(sort file1) <(sort file2)

# Loop over files
for f in *.txt; do echo "$f"; done

# Loop over lines
while read -r line; do echo "$line"; done < file.txt

See Also

• Shell — Scripting patterns, loops, conditionals, functions
• jq — JSON processing in pipelines
• CLI Pipelines: Keeping Data in the Stream
• Unix Filesystem (Advanced)
• Unix Filesystem
• HTTP
• macOS CLI
• CLI-First
• Networking Lesson Plan
• Operating Systems Lesson Plan