Here’s a quick reference guide to essential Linux commands.
It covers common file operations, system administration tasks, user management, network commands, and more.
1. File and Directory Operations
ls – List files and directories.
ls # List files in the current directory
ls -l # List files with details (permissions, size, etc.)
ls -a # List all files, including hidden ones
ls -lh # List files with human-readable sizes (e.g., KB, MB)cd – Change directory.
cd /path/to/directory # Change to specified directory
cd ~ # Change to home directory
cd .. # Go up one directory levelpwd – Print working directory.
pwd # Show the current directory pathmkdir – Create a directory.
mkdir newdir # Create a directory named 'newdir'
mkdir -p /path/to/dir # Create intermediate directories as neededrmdir – Remove an empty directory.
rmdir mydir # Remove the empty directory 'mydir'rm – Remove files or directories.
rm file.txt # Delete a file
rm -r mydir # Delete a directory and its contents
rm -rf mydir # Forcefully delete a directory (ignores warnings)cp – Copy files and directories.
cp file1.txt file2.txt # Copy file1.txt to file2.txt
cp -r dir1/ dir2/ # Copy a directory and its contentsmv – Move or rename files and directories.
mv file1.txt file2.txt # Rename file1.txt to file2.txt
mv file.txt /path/to/dir/ # Move file.txt to another directoryfind – Search for files and directories.
find /path -name "filename" # Find files by name
find /path -type f -name "*.txt" # Find all .txt fileslocate – Find files by name (faster than find if database is up-to-date).
locate filename # Locate a file by name
updatedb # Update the database for `locate` (needs root)touch – Create an empty file or update file timestamps.
touch file.txt # Create an empty file or update file timestamp 2. File Permissions
chmod – Change file permissions.
chmod 755 file.txt # Set rwx for owner, rx for group and others
chmod +x file.sh # Make a file executable
chmod -r 644 file.txt # Set permissions recursivelychown – Change file ownership.
chown user:group file.txt # Change ownership to user and group
chown -R user:group /path # Recursively change ownershipchgrp – Change group ownership.
chgrp group file.txt # Change group ownership of a file 3. Process Management
ps – Show current processes.
ps # Show current processes for the user
ps aux # Show all processes (user and system-wide)
ps -ef # Show detailed process information (full format)top – Show system resource usage and process list (interactive).
top # Start top command to show system resource usagehtop – Enhanced version of top (requires installation).
htop # Interactive process viewer with better UIkill – Kill a process by PID.
kill PID # Terminate a process by its PID
kill -9 PID # Forcefully kill a process (SIGKILL)killall – Kill processes by name.
killall process_name # Kill all processes by namebg – Resume a job in the background.
bg %1 # Resume job 1 in the backgroundfg – Bring a job to the foreground.
fg %1 # Bring job 1 to the foreground 4. Disk Usage
df – Show disk space usage.
df # Display free disk space for mounted filesystems
df -h # Human-readable format (GB, MB)du – Show disk usage of files and directories.
du -sh /path/to/dir # Show total size of directory
du -ah /path/to/dir # Show size of all files and directoriesmount – Mount a filesystem or view mounted filesystems.
mount # Show all mounted filesystems
mount /dev/sdX /mnt # Mount a filesystem to a directoryumount – Unmount a filesystem.
umount /mnt # Unmount the filesystem mounted at /mnt 5. Network Commands
ping – Check network connectivity.
ping google.com # Ping a remote host
ping -c 4 google.com # Ping 4 times and stopifconfig – Show network interface configuration (deprecated, use ip).
ifconfig # Show all network interfaces and their detailsip – Show or configure network interfaces (modern alternative to ifconfig).
ip a # Show all network interfaces
ip addr show # Show detailed network interface informationnetstat – Network statistics and connections.
netstat -tuln # Show listening ports and active connectionsss – Utility to investigate sockets (modern replacement for netstat).
ss -tuln # Show listening ports and active connectionsscp – Securely copy files between hosts.
scp file.txt user@remote:/path/to/destination # Copy file to remote server
scp user@remote:/path/to/file.txt /local/path # Copy file from remote serverssh – Securely connect to a remote server.
ssh user@remote_host # SSH into a remote hostwget – Download files from the web.
wget http://example.com/file.zip # Download a filecurl – Transfer data from or to a server.
curl -O http://example.com/file.zip # Download a file with curl 6. File Compression and Archiving
tar – Archive files.
tar -cvf archive.tar file1 file2 # Create a tar archive
tar -xvf archive.tar # Extract a tar archive
tar -cvzf archive.tar.gz files # Create a gzipped tar archive
tar -xvzf archive.tar.gz # Extract a gzipped tar archivegzip – Compress files using gzip.
gzip file.txt # Compress file.txt into file.txt.gz
gunzip file.txt.gz # Decompress file.txt.gzzip – Create a ZIP archive.
zip archive.zip file1 file2 # Create a zip archive
unzip archive.zip # Extract a zip archive 7. System Information
uname – Show system information.
uname -a # Show all system information (kernel, OS, etc.)
uname -r # Show kernel versionuptime – Show how long the system has been running.
uptime # Show system uptimedmesg – Show kernel ring buffer messages (system startup logs).
dmesg # Show the kernel ring buffer messagesfree – Show memory usage.
free -h # Show memory usage in human-readable formattop – View system resource usage (CPU, memory, processes).
top # Interactive process viewervmstat – Report system performance (memory, processes, CPU).
vmstat # Show system performance statistics 8. User Management
whoami – Show current logged-in user.
whoami # Show the current logged-in useradduser – Add a new user.
sudo adduser username # Create a new userpasswd – Change user password.
sudo passwd username # Change password for a useruserdel – Delete a user.
sudo userdel username # Delete a usergroupadd – Add a new group.
sudo groupadd groupname # Create a new groupgroups – Show the groups a user belongs to.
groups username # Show groups for a user 9. Searching Files and Content
grep – Search for text in files.
grep "search_term" file.txt # Search for 'search_term' in file.txt
grep -r "search_term" /dir # Search recursively in a directorywhich – Show the path of an executable.
which python # Show path of the python executablefind – Search for files and directories.
find /path -name "filename" # Find files by name
find /path -type f -name "*.txt" # Find .txt filesThis cheat sheet covers many of the most frequently used commands in Linux, but there’s always more to explore!
Let me know if you need help with any specific command or additional topics. aungkyawnyut2004@gmail.com
Let me know if you need help with any specific command or additional topics. aungkyawnyut2004@gmail.com
Happy Codding ;)
