🐧 Linux Command Cheat Sheet
Complete reference for essential Linux commands with examples, syntax, and practical usage tips
List directory contents
Syntax:
ls [options] [directory]Examples:
ls List files in current directory
ls -la List all files including hidden with detailed info
ls -lh List with human-readable file sizes
ls *.txt List only .txt files
Notes:
Common options: -l (long format), -a (all files), -h (human readable), -R (recursive)
Copy files and directories
Syntax:
cp [options] source destinationExamples:
cp file.txt backup.txt Copy file to new name
cp -r folder/ backup/ Copy directory recursively
cp *.txt /backup/ Copy all .txt files to backup directory
cp -p file.txt /dest/ Copy preserving attributes
Notes:
Use -r for directories, -p to preserve permissions and timestamps
Move/rename files and directories
Syntax:
mv [options] source destinationExamples:
mv oldname.txt newname.txt Rename a file
mv file.txt /new/location/ Move file to different directory
mv *.txt documents/ Move all .txt files to documents folder
mv folder1/ folder2/ Rename/move directory
Notes:
Works for both moving and renaming files and directories
Remove files and directories
Syntax:
rm [options] file/directoryExamples:
rm file.txt Delete a file
rm -r folder/ Delete directory and contents recursively
rm -f file.txt Force delete without confirmation
rm *.tmp Delete all .tmp files
Notes:
Be careful! -f forces deletion, -r removes directories recursively
Create empty files or update timestamps
Syntax:
touch [options] filenameExamples:
touch newfile.txt Create empty file
touch file1.txt file2.txt Create multiple files
touch -t 202312250800 file.txt Set specific timestamp
Notes:
Creates file if it doesn't exist, updates timestamp if it does
Create links between files
Syntax:
ln [options] target linknameExamples:
ln file.txt hardlink.txt Create hard link
ln -s /path/to/file symlink Create symbolic link
ln -sf /new/target existing_link Force create/update symbolic link
Notes:
Use -s for symbolic links, hard links share same inode
Print working directory
Syntax:
pwdExamples:
pwd Show current directory path
Notes:
Displays the full path of current directory
Change directory
Syntax:
cd [directory]Examples:
cd /home/user Change to specific directory
cd .. Go up one directory level
cd ~ Go to home directory
cd - Go to previous directory
Notes:
~ represents home directory, .. means parent directory
Create directories
Syntax:
mkdir [options] directoryExamples:
mkdir newdir Create single directory
mkdir -p path/to/deep/dir Create nested directories
mkdir dir1 dir2 dir3 Create multiple directories
mkdir -m 755 mydir Create with specific permissions
Notes:
Use -p to create parent directories if they don't exist
Remove empty directories
Syntax:
rmdir [options] directoryExamples:
rmdir emptydir Remove empty directory
rmdir -p path/to/empty/dirs Remove empty directory hierarchy
Notes:
Only works on empty directories, use 'rm -r' for non-empty directories
Display file contents
Syntax:
cat [options] fileExamples:
cat file.txt Display file contents
cat file1.txt file2.txt Display multiple files
cat -n file.txt Display with line numbers
cat > newfile.txt Create file from input
Notes:
Can concatenate multiple files, use > to redirect output
View file contents page by page
Syntax:
less [options] fileExamples:
less file.txt View file with pagination
less +50 file.txt Start at line 50
command | less Pipe command output to less
Notes:
Use space/f for next page, b for previous, q to quit, / to search
Display first lines of file
Syntax:
head [options] fileExamples:
head file.txt Show first 10 lines
head -n 20 file.txt Show first 20 lines
head -c 100 file.txt Show first 100 characters
Notes:
Default shows first 10 lines, use -n to specify number of lines
Display last lines of file
Syntax:
tail [options] fileExamples:
tail file.txt Show last 10 lines
tail -n 20 file.txt Show last 20 lines
tail -f logfile.txt Follow file changes in real-time
tail -F logfile.txt Follow file even if recreated
Notes:
Use -f to monitor log files, -F handles file rotation
Search text patterns in files
Syntax:
grep [options] pattern fileExamples:
grep 'error' logfile.txt Search for 'error' in file
grep -i 'ERROR' file.txt Case insensitive search
grep -r 'pattern' directory/ Recursive search in directory
grep -v 'exclude' file.txt Show lines NOT containing pattern
Notes:
Use -i for case insensitive, -r for recursive, -v to invert match
Stream editor for filtering and transforming text
Syntax:
sed [options] 'command' fileExamples:
sed 's/old/new/g' file.txt Replace all occurrences of 'old' with 'new'
sed -i 's/old/new/g' file.txt Replace in-place (modify original file)
sed -n '10,20p' file.txt Print lines 10 to 20
sed '/pattern/d' file.txt Delete lines containing pattern
Notes:
Powerful stream editor, use -i to modify files in place
Pattern scanning and processing language
Syntax:
awk 'pattern {action}' fileExamples:
awk '{print $1}' file.txt Print first column
awk -F: '{print $1}' /etc/passwd Use colon as field separator
awk 'length > 80' file.txt Print lines longer than 80 characters
awk '{sum+=$1} END {print sum}' file.txt Sum first column values
Notes:
Powerful text processing tool, $1, $2, etc. refer to columns
Sort lines in text files
Syntax:
sort [options] fileExamples:
sort file.txt Sort lines alphabetically
sort -n numbers.txt Sort numerically
sort -r file.txt Sort in reverse order
sort -k2 file.txt Sort by second column
Notes:
Use -n for numeric sort, -r for reverse, -k to specify sort column
Remove duplicate adjacent lines
Syntax:
uniq [options] fileExamples:
uniq file.txt Remove duplicate adjacent lines
sort file.txt | uniq Sort then remove all duplicates
uniq -c file.txt Count occurrences of each line
uniq -d file.txt Show only duplicate lines
Notes:
Only removes adjacent duplicates, often used with sort
Count lines, words, and characters
Syntax:
wc [options] fileExamples:
wc file.txt Count lines, words, and characters
wc -l file.txt Count only lines
wc -w file.txt Count only words
wc -c file.txt Count only characters
Notes:
Default shows lines, words, and characters count
Display running processes
Syntax:
ps [options]Examples:
ps Show processes for current terminal
ps aux Show all processes with detailed info
ps -ef Show all processes in full format
ps -u username Show processes for specific user
Notes:
Common options: aux (all processes), -ef (full format), -u (by user)
Display running processes dynamically
Syntax:
top [options]Examples:
top Show real-time process information
top -u username Show processes for specific user
top -p PID Monitor specific process
Notes:
Interactive tool: q to quit, k to kill process, r to renice
Interactive process viewer (enhanced top)
Syntax:
htop [options]Examples:
htop Launch interactive process viewer
htop -u username Show processes for specific user
Notes:
More user-friendly than top, requires installation on many systems
Display disk space usage
Syntax:
df [options] [filesystem]Examples:
df Show disk usage for all filesystems
df -h Show in human-readable format
df -T Show filesystem types
df /home Show usage for specific mount point
Notes:
Use -h for human-readable sizes (GB, MB, etc.)
Display directory space usage
Syntax:
du [options] [directory]Examples:
du -h Show directory sizes in human-readable format
du -sh * Show size of each item in current directory
du -sh /var/log Show total size of specific directory
du -h --max-depth=1 Show sizes one level deep
Notes:
Use -h for human-readable, -s for summary, --max-depth to limit recursion
Display memory usage
Syntax:
free [options]Examples:
free Show memory usage in KB
free -h Show in human-readable format
free -m Show in MB
free -s 5 Update every 5 seconds
Notes:
Shows total, used, free, shared, buffer/cache, and available memory
Display system information
Syntax:
uname [options]Examples:
uname Show kernel name
uname -a Show all system information
uname -r Show kernel release
uname -m Show machine architecture
Notes:
Common options: -a (all), -r (kernel release), -m (machine type)
Display current username
Syntax:
whoamiExamples:
whoami Show current user
Notes:
Simple command to check which user you're logged in as
Display user and group IDs
Syntax:
id [username]Examples:
id Show current user's UID, GID, and groups
id username Show specific user's ID information
id -u Show only user ID
id -g Show only group ID
Notes:
Shows UID (user ID), GID (group ID), and all group memberships
Terminate processes by PID
Syntax:
kill [signal] PIDExamples:
kill 1234 Send TERM signal to process 1234
kill -9 1234 Force kill process 1234
kill -HUP 1234 Send hangup signal to reload config
kill -l List all available signals
Notes:
Common signals: -9 (KILL), -15 (TERM), -1 (HUP), -2 (INT)
Terminate processes by name
Syntax:
killall [options] processnameExamples:
killall firefox Kill all firefox processes
killall -9 python Force kill all python processes
killall -u username Kill all processes owned by user
Notes:
Kills processes by name instead of PID, be careful with common names
Display active jobs
Syntax:
jobs [options]Examples:
jobs List active jobs
jobs -l List jobs with PID
jobs -r List only running jobs
Notes:
Shows background jobs started from current shell
Put jobs in background
Syntax:
bg [job]Examples:
bg Put most recent job in background
bg %1 Put job 1 in background
Notes:
Use after Ctrl+Z to suspend, then bg to continue in background
Bring jobs to foreground
Syntax:
fg [job]Examples:
fg Bring most recent job to foreground
fg %1 Bring job 1 to foreground
Notes:
Brings background or suspended jobs back to foreground
Run commands immune to hangups
Syntax:
nohup command [args] &Examples:
nohup python script.py & Run script in background, immune to logout
nohup ./long-running-task > output.log 2>&1 & Run with output redirection
Notes:
Prevents process from being killed when terminal closes
Send ICMP echo requests to network hosts
Syntax:
ping [options] hostname/IPExamples:
ping google.com Ping Google continuously
ping -c 4 8.8.8.8 Ping 4 times then stop
ping -i 2 hostname Ping every 2 seconds
Notes:
Use Ctrl+C to stop, -c to limit count, -i to set interval
Download files from web
Syntax:
wget [options] URLExamples:
wget https://example.com/file.zip Download file
wget -O output.zip https://example.com/file.zip Download with custom name
wget -r https://example.com/ Download website recursively
wget -c https://example.com/largefile.zip Resume interrupted download
Notes:
Use -O for output filename, -c to resume downloads, -r for recursive
Transfer data from/to servers
Syntax:
curl [options] URLExamples:
curl https://api.example.com GET request to API
curl -O https://example.com/file.zip Download file
curl -X POST -d 'data' https://api.example.com POST request with data
curl -H 'Content-Type: application/json' -d '{"key":"value"}' https://api.example.com POST JSON data
Notes:
More versatile than wget, supports many protocols and HTTP methods
Secure Shell remote login
Syntax:
ssh [user@]hostname [command]Examples:
ssh user@server.com Connect to remote server
ssh -p 2222 user@server.com Connect using specific port
ssh user@server.com 'ls -la' Execute command on remote server
ssh -L 8080:localhost:80 user@server.com Create local port forwarding
Notes:
Use -p for custom port, -L for port forwarding, -X for X11 forwarding
Secure copy files over SSH
Syntax:
scp [options] source destinationExamples:
scp file.txt user@server:/path/ Copy file to remote server
scp user@server:/path/file.txt . Copy file from remote server
scp -r folder/ user@server:/path/ Copy directory recursively
scp -P 2222 file.txt user@server:/path/ Use specific port
Notes:
Like cp but over SSH, use -r for directories, -P for port
Change file permissions
Syntax:
chmod [options] mode fileExamples:
chmod 755 script.sh Set rwxr-xr-x permissions
chmod +x script.sh Add execute permission
chmod u+w,g-r file.txt Add write for user, remove read for group
chmod -R 644 directory/ Set permissions recursively
Notes:
Numeric: 4=read, 2=write, 1=execute. Symbolic: u=user, g=group, o=other, a=all
Change file ownership
Syntax:
chown [options] owner[:group] fileExamples:
chown user file.txt Change owner to user
chown user:group file.txt Change owner and group
chown :group file.txt Change only group
chown -R user:group directory/ Change ownership recursively
Notes:
Use -R for recursive, format is owner:group
Change group ownership
Syntax:
chgrp [options] group fileExamples:
chgrp staff file.txt Change group to staff
chgrp -R developers project/ Change group recursively
Notes:
Changes only group ownership, use -R for recursive
Set default file permissions
Syntax:
umask [mode]Examples:
umask Show current umask
umask 022 Set umask to 022 (755 for dirs, 644 for files)
umask 077 Set restrictive umask (700 for dirs, 600 for files)
Notes:
Umask subtracts from default permissions (777 for dirs, 666 for files)
Archive files and directories
Syntax:
tar [options] archive filesExamples:
tar -czf archive.tar.gz folder/ Create compressed archive
tar -xzf archive.tar.gz Extract compressed archive
tar -tzf archive.tar.gz List contents of archive
tar -xzf archive.tar.gz -C /destination/ Extract to specific directory
Notes:
Common options: c=create, x=extract, z=gzip, f=file, t=list, v=verbose
Compress files
Syntax:
gzip [options] fileExamples:
gzip file.txt Compress file (creates file.txt.gz)
gzip -d file.txt.gz Decompress file
gzip -k file.txt Compress but keep original
gzip -9 file.txt Maximum compression
Notes:
Use -d to decompress, -k to keep original, -9 for best compression
Extract ZIP archives
Syntax:
unzip [options] archive.zipExamples:
unzip archive.zip Extract all files
unzip archive.zip -d /destination/ Extract to specific directory
unzip -l archive.zip List contents without extracting
unzip archive.zip file.txt Extract specific file
Notes:
Use -d for destination, -l to list, can extract specific files
Create ZIP archives
Syntax:
zip [options] archive.zip filesExamples:
zip archive.zip file1.txt file2.txt Create archive with files
zip -r archive.zip folder/ Create archive with directory
zip -u archive.zip newfile.txt Update archive with new file
zip -9 archive.zip file.txt Maximum compression
Notes:
Use -r for recursive (directories), -u to update, -9 for best compression
Search for files and directories
Syntax:
find [path] [expression]Examples:
find . -name '*.txt' Find all .txt files in current directory
find /home -user john Find files owned by user john
find . -type f -size +100M Find files larger than 100MB
find . -name '*.log' -mtime -7 Find .log files modified in last 7 days
Notes:
Very powerful, use -name for filename, -type for file type, -size for size, -mtime for modification time
Find files by name (using database)
Syntax:
locate [options] patternExamples:
locate filename.txt Find files named filename.txt
locate -i pattern Case insensitive search
locate '*.conf' Find all .conf files
Notes:
Fast but requires updatedb to be run regularly, searches indexed database
Locate command executable
Syntax:
which commandExamples:
which python Find path to python executable
which -a python Show all python executables in PATH
Notes:
Shows full path of executable commands, useful for finding binary locations
Locate binary, source, manual pages
Syntax:
whereis [options] commandExamples:
whereis python Find python binary, source, and manual
whereis -b python Find only binary
whereis -m python Find only manual pages
Notes:
More comprehensive than which, finds binaries, sources, and manuals
Execute commands as another user
Syntax:
sudo [options] commandExamples:
sudo apt update Run command as root
sudo -u username command Run command as specific user
sudo -i Start interactive root shell
sudo !! Run previous command with sudo
Notes:
Requires user to be in sudoers file, use -i for interactive shell
Switch user
Syntax:
su [options] [username]Examples:
su Switch to root user
su username Switch to specific user
su - Switch to root with full environment
su - username Switch user with full environment
Notes:
Use - to get full environment, exit to return to original user
Control systemd services
Syntax:
systemctl [command] [service]Examples:
systemctl status nginx Check service status
systemctl start nginx Start service
systemctl stop nginx Stop service
systemctl enable nginx Enable service at boot
systemctl list-units List all active units
Notes:
Modern way to manage services on systemd systems
Control system services (legacy)
Syntax:
service [service] [command]Examples:
service nginx status Check service status
service nginx start Start service
service nginx restart Restart service
service --status-all List all services and their status
Notes:
Older service management, use systemctl on modern systems
Package manager for Debian/Ubuntu
Syntax:
apt [options] command [package]Examples:
apt update Update package list
apt upgrade Upgrade installed packages
apt install package Install package
apt remove package Remove package
apt search keyword Search for packages
Notes:
Modern replacement for apt-get, requires sudo for most operations
Package manager for Red Hat/CentOS
Syntax:
yum [options] command [package]Examples:
yum update Update all packages
yum install package Install package
yum remove package Remove package
yum search keyword Search for packages
yum list installed List installed packages
Notes:
Package manager for RHEL-based systems, being replaced by dnf
Package manager for Fedora/RHEL 8+
Syntax:
dnf [options] command [package]Examples:
dnf update Update all packages
dnf install package Install package
dnf remove package Remove package
dnf search keyword Search for packages
dnf history Show transaction history
Notes:
Modern replacement for yum in Fedora and RHEL 8+
Display or set environment variables
Syntax:
env [options] [variable=value] [command]Examples:
env Display all environment variables
env PATH=/custom/path command Run command with modified PATH
env -i command Run command with empty environment
Notes:
Use without arguments to see all environment variables
Set environment variables
Syntax:
export [variable[=value]]Examples:
export PATH=$PATH:/new/path Add to PATH variable
export EDITOR=vim Set default editor
export Show all exported variables
Notes:
Makes variables available to child processes
Display text
Syntax:
echo [options] [text]Examples:
echo 'Hello World' Print text
echo $PATH Print environment variable
echo -n 'No newline' Print without newline
echo -e 'Line 1\nLine 2' Interpret escape sequences
Notes:
Use -n to suppress newline, -e to enable escape sequences
Display command history
Syntax:
history [options]Examples:
history Show command history
history 10 Show last 10 commands
history -c Clear history
!123 Execute command number 123 from history
Notes:
Use !n to repeat command n, !! for last command, !string for last command starting with string
Create command aliases
Syntax:
alias [name[=value]]Examples:
alias ll='ls -la' Create alias for long listing
alias Show all aliases
alias grep='grep --color=auto' Make grep colorful by default
Notes:
Aliases are temporary unless added to shell configuration files
🚀 Linux Pro Tips
Essential Keyboard Shortcuts
Ctrl+C- Interrupt current commandCtrl+Z- Suspend current processCtrl+D- Exit current shell/EOFCtrl+L- Clear screenCtrl+R- Search command historyTab- Auto-complete commands/paths
Common Command Combinations
command | less- Paginate outputcommand > file.txt- Redirect output to filecommand >> file.txt- Append output to filecommand 2>&1- Redirect errors to outputcommand &- Run in backgroundcommand1 && command2- Run command2 if command1 succeeds
⚠️ Safety Tips
- • Always double-check
rmcommands, especially with-rand-fflags - • Use
lsto verify paths before running destructive commands - • Test commands on non-critical files first
- • Use
sudocarefully - it grants full system access - • Make backups before making system changes
📚 Keep Learning
Master Linux with these essential practices:
📖 Read Man Pages
Use man command for detailed documentation
🛠️ Practice Regularly
Use a virtual machine or container for safe practice
🔍 Explore Options
Try command --help for quick option lists