Common Linux Commands

Here’s a list of Linux commands, with their options (if any) that you can run within the terminal for the most common tasks. Give them a try and make the best use of your Linux OS!

1. System Navigation & File Management

• pwd — Prints the current working directory path.
• ls — Lists files and directories in the current directory.
  Options:
  • -l — Use long listing format (detailed view).
  • -a — Show all files, including hidden ones (starting with .).
  • -h — Display file sizes in human-readable format (e.g., KB, MB).
  • -R — List contents of subdirectories recursively.
  • --color=auto — Enable colored output to distinguish file types.
• cd — Changes the current directory.
  Common usages:
  • cd .. — Move up one directory level.
  • cd / — Move to the root directory.
  • cd ~ — Move to the home directory.
• tree — Displays the directory structure in a tree-like format.
  Options:
  • -L N — Limit display to N directory levels.
  • -a — Include hidden files.
• find — Searches for files and directories in a hierarchy.
  Options:
  • -name pattern — Search by file name.
  • -type f — Search only for files.
  • -type d — Search only for directories.
  • -size +100M — Find files larger than 100 MB.
  • -mtime N — Find files modified N days ago.
  • -exec command {} \; — Execute a command on each found item.
• locate — Quickly searches for files by name using a prebuilt database.
• file — Determines the type of a given file.
• stat — Displays detailed file or directory information (size, permissions, timestamps).
• touch — Creates an empty file or updates its access and modification timestamps.
• cp — Copies files or directories.
  Options:
  • -r — Copy directories recursively.
  • -v — Show progress for each copied file.
  • -u — Copy only when the source file is newer.
  • -i — Prompt before overwriting existing files.
• mv — Moves or renames files and directories.
  Options:
  • -i — Prompt before overwrite.
  • -v — Show progress.
• rm — Removes files or directories.
  Options:
  • -r — Delete directories recursively.
  • -f — Force delete without prompting.
  • -i — Ask for confirmation before each removal.
• mkdir — Creates directories.
  Options:
  • -p — Create parent directories if needed.
  • -v — Show directories as they’re created.
• rmdir — Removes empty directories.
• cat — Displays file contents, concatenates, or creates files.
  Options:
  • -n — Number all output lines.
• less — Views file contents one screen at a time (scrollable).
• head — Displays the first lines of a file.
  Options:
  • -n N — Show the first N lines.
• tail — Displays the last lines of a file.
  Options:
  • -n N — Show the last N lines.
  • -f — Follow a file as it grows (e.g., log files).

2. File Permissions & Ownership

• chmod — Changes file or directory permissions.
  Common usages:
  • chmod 755 file — Owner: read/write/execute; others: read/execute.
  • chmod +x file — Add execute permission.
  • chmod -R directory — Apply permissions recursively.
• chown — Changes ownership of a file or directory.
• chgrp — Changes the group ownership of a file or directory.
• umask — Sets default permissions for new files and directories.

3. Compression & Archiving

• tar — Archives multiple files into one.
  Options:
  • -c — Create a new archive.
  • -x — Extract from an archive.
  • -v — Verbose output (list processed files).
  • -f — Specify archive file name.
  • -z — Compress with gzip.
  • -j — Compress with bzip2.
  • -t — List archive contents.
• gzip — Compresses files.
  Options:
  • -r — Compress files recursively.
  • -v — Show compression details.
• gunzip — Decompresses .gz files.
• zip — Creates zip archives.
  Options:
  • -r — Recursively include directories.
  • -v — Verbose output.
• unzip — Extracts zip archives.
  Options:
  • -l — List archive contents.
  • -v — Verbose mode.

4. System Information

• uname — Displays system and kernel information.
  Options:
  • -a — Show all system information.
  • -r — Show kernel release.
  • -n — Show network hostname.
• hostname — Shows or sets the system’s hostname.
  Options:
  • -I — Display system’s IP addresses.
• uptime — Displays system uptime and load average.
• date — Displays or sets the system date and time.
  Options:
  • +%Y-%m-%d — Show date in year-month-day format.
• cal — Displays a calendar for the current month or year.
• free — Displays memory usage.
  Options:
  • -h — Human-readable units (e.g., MB, GB).
• top — Displays dynamic, real-time view of running processes.
• lscpu — Shows information about CPU architecture.
• lsblk — Lists block devices (drives and partitions).
• dmesg — Displays kernel messages, including boot and hardware logs.

5. Process Management

• ps — Displays running processes.
  Options:
  • aux — Show all processes in detail.
  • -ef — Full-format listing with parent-child relationships.
• kill — Terminates a process by PID.
  Options:
  • -9 — Force kill immediately.
  • -15 — Graceful termination (default).
• pkill — Kills processes by name.
• nice — Starts a process with a specified priority.
• renice — Changes the priority of a running process.
• jobs — Lists current background jobs.
• bg — Resumes a job in the background.
• fg — Brings a background job to the foreground.

6. Networking

• ping — Tests connectivity to a host.
  Options:
  • -c N — Send N packets.
  • -i N — Wait N seconds between packets.
• ip — Displays or configures network interfaces.
  Examples:
  • ip addr — Show IP addresses.
  • ip route — Show routing table.
• netstat — Displays network connections and routing tables.
  Options:
  • -t — TCP connections.
  • -u — UDP connections.
  • -l — Listening sockets.
  • -n — Show numeric addresses.
  • -p — Show process IDs and names.
• ss — A faster alternative to netstat.
  Options:
  • -tuln — Show listening TCP and UDP ports.
• curl — Transfers data from or to a URL.
  Options:
  • -I — Fetch only HTTP headers.
  • -O — Save file with its original name.
  • -L — Follow redirects.
• wget — Downloads files via HTTP/HTTPS/FTP.
  Options:
  • -c — Continue interrupted downloads.
  • -b — Run in background.
  • -r — Recursive download.
• scp — Securely copies files between hosts.
  Options:
  • -r — Copy directories recursively.
  • -P — Specify remote port number.
• ssh — Connects securely to a remote host.
  Options:
  • -p — Specify port.
  • -i — Use an identity (private key) file.

7. User & Group Management

• whoami — Displays the current username.
• id — Displays user and group IDs.
• adduser — Creates a new user account.
• passwd — Changes a user password.
• usermod — Modifies an existing user account.
  Options:
  • -aG group — Add user to a group.
  • -s shell — Change user shell.
  • -d dir — Change home directory.
• sudo — Runs commands as the root user or another user.

8. Text Processing

• grep — Searches for text patterns in files.
  Options:
  • -i — Case-insensitive search.
  • -r — Recursive search.
  • -n — Show line numbers.
  • --color — Highlight matches.
• awk — Scans and processes text using patterns and actions.
• sed — Stream editor for modifying text.
  Options:
  • -i — Edit files in place.
  • s/pattern/replacement/ — Substitute text.
• sort — Sorts lines of text files.
  Options:
  • -r — Reverse order.
  • -n — Numeric sort.
  • -u — Remove duplicates.
• uniq — Filters or counts duplicate lines.
  Options:
  • -c — Prefix lines with counts.
  • -d — Show only duplicates.
• wc — Counts words, lines, or characters.
  Options:
  • -l — Count lines.
  • -w — Count words.
  • -c — Count bytes.

9. System Administration

• systemctl — Controls and manages systemd services.
  Options:
  • start service — Start a service.
  • stop service — Stop a service.
  • status service — View status.
  • enable service — Auto-start at boot.
  • disable service — Disable autostart.
• journalctl — Displays system logs.
  Options:
  • -xe — Show recent errors and logs.
  • -u service — Show logs for a specific service.
• shutdown — Shuts down or restarts the system.
  Options:
  • -h now — Halt immediately.
  • -r now — Reboot immediately.
• reboot — Reboots the system immediately.
• history — Displays command history.
  Options:
  • !N — Re-execute command number N.
  • grep text — Filter history results.

10. Disk & Storage Management

• fdisk — Command-line utility to manage disk partitions.
  Options:
  • -l — List all available disks and their partition tables.
  • fdisk /dev/sdX — Open a specific disk for partitioning (replace sdX with actual disk ID).
• lsblk — Lists all block devices (disks, partitions, USBs) in a tree format.
  Options:
  • -f — Show filesystem type and UUID.
  • -o — Customize displayed columns (e.g., lsblk -o NAME,SIZE,MOUNTPOINT).
• blkid — Displays attributes (UUID, filesystem type) of block devices.
• mount — Mounts a filesystem or device to a directory.
  Examples / options:
  • mount /dev/sdX1 /mnt — Mounts a partition to /mnt.
  • -t type — Specify filesystem type (e.g., ext4, ntfs).
  • -o option — Use mount options (e.g., ro, rw, noexec).
• umount — Unmounts a mounted filesystem or device.
  Examples / options:
  • umount /mnt — Unmounts /mnt.
  • umount /dev/sdX1 — Unmounts the device directly.
  • -f — Force unmount (use cautiously).
• df — Displays disk space usage for mounted filesystems.
  Options:
  • -h — Human-readable sizes (KB, MB, GB).
  • -T — Show filesystem type.
  • -a — Include pseudo and temporary filesystems.
• du — Displays disk usage of files and directories.
  Options:
  • -h — Human-readable sizes.
  • -s — Show only total size per directory.
  • --max-depth=N — Limit recursion to N levels.
• mkfs — Creates a new filesystem on a partition.
  Examples / options:
  • mkfs.ext4 /dev/sdX1 — Create an EXT4 filesystem on partition sdX1.
  • -t type — Specify filesystem type.
  • -L label — Set a volume label.
• fsck — Checks and repairs filesystem errors.
  Examples / options:
  • fsck /dev/sdX1 — Check and repair a partition.
  • -y — Automatically fix detected errors.
  • -n — Perform a dry run (no changes made).
• dd — Low-level utility for copying and converting raw data (e.g., cloning disks).
  Options:
  • if=file — Specify input file (or device).
  • of=file — Specify output file (or device).
  • bs=size — Set block size (e.g., bs=4M).
  • status=progress — Show copy progress.
• parted — Disk partition manipulation tool (similar to fdisk, supports GPT).
  Options:
  • -l — List partitions.
  • mklabel gpt — Create a new GPT partition table.
  • mkpart — Create a new partition.

11. Package Management

🟩 Debian / Ubuntu (apt & dpkg)

• apt update — Updates the package list from repositories.
• apt upgrade — Upgrades all upgradable packages to newer versions.
• apt install package — Installs a package from repositories.
  Options:
  • -y — Automatically answer “yes” to prompts.
  • --reinstall — Reinstall an existing package.
• apt remove package — Removes a package but keeps configuration files.
  Options:
  • -y — Auto confirm removal.
• apt purge package — Removes a package and its configuration files.
• apt autoremove — Removes automatically installed dependencies no longer needed.
• apt search keyword — Searches for a package by keyword.
• apt show package — Displays detailed information about a package.
• dpkg -l — Lists installed packages.
• dpkg -i package.deb — Installs a .deb package manually.
• dpkg -r package — Removes a manually installed package.

🟥 RHEL / CentOS / Fedora (yum & dnf)

• yum install package — Installs a package.
• yum remove package — Removes a package.
• yum update — Updates all packages to the latest version.
• yum list installed — Lists all installed packages.
• yum search keyword — Searches for a package by name or keyword.
• dnf — Modern replacement for yum with same syntax and improved performance.

🟦 Arch Linux (pacman)

• pacman -S package — Installs a package.
• pacman -R package — Removes a package.
• pacman -Syu — Updates package database and all installed packages.
• pacman -Qs keyword — Searches for packages by keyword.
• pacman -Qi package — Shows detailed information about a package.

12. Scripting & Automation

• bash — Runs Bash shell or executes a shell script file.
  Example:
  • bash script.sh — Executes script.sh.
• sh — Executes shell scripts (POSIX compliant, simpler than Bash).
• echo — Prints text or variables to the terminal.
  Options:
  • -n — Do not print a newline.
  • -e — Enable interpretation of backslash escapes (e.g., \n, \t).
  • Example: echo -e "Line 1\nLine 2" — Prints two lines.
• read — Reads user input into a variable in scripts.
  • Example: read name — Waits for input and stores it in name.
• export — Sets or exports environment variables.
  • Example: export PATH=$PATH:/usr/local/bin — Adds a directory to PATH.
• alias — Creates shortcuts for commands.
  • Example: alias ll='ls -lah' — Defines ll as a shortcut for listing files in long format.
• cron — Time-based job scheduler for repetitive tasks.
• crontab — Installs, edits, or lists scheduled jobs for the current user.
  Options:
  • -e — Edit the current user’s cron jobs.
  • -l — List all cron jobs.
  • -r — Remove all cron jobs.
  • Example: crontab -e then add: 0 2 * * * /path/to/script.sh — Run script daily at 2 AM.
• at — Schedules a one-time command execution at a specific time.
  • Example: at 10:30 → then type your command → Ctrl+D to save.
• which — Shows the full path of a command or executable.
• type — Displays how a command name is interpreted (alias, builtin, or external).
• sleep — Delays execution for a given number of seconds.
  • Example: sleep 5 — Wait for 5 seconds.
• seq — Prints a sequence of numbers.
  • Example: seq 1 5 → prints 1 2 3 4 5.
• printf — Prints formatted text (more powerful than echo).
  • Example: printf "Name: %s\nAge: %d\n" "Alice" 18
• exit — Exits the current shell or script with a return code.
  Example:
  • exit 0 — Exit successfully.
  • exit 1 — Exit with an error.
• trap — Catches and handles signals in scripts.
  • Example: trap "echo Interrupted!" SIGINT — Print message when user presses Ctrl+C.
• source — Executes commands from a file in the current shell environment.
  • Example: source ~/.bashrc — Reloads shell configuration.

Go open source!