Linux Command Repository

Introduction

Welcome to the Linux Command Repository! This repository is a collection of Linux commands suitable for beginners and advanced users. Whether you are new to Linux or looking to expand your command-line knowledge, this resource is here to help you.

What is Linux?

Linux is a popular open-source operating system known for its power, flexibility, and robust command-line interface. Learning how to use Linux commands is essential for efficient system administration, development, and automation tasks.

Commands

Below is a list of commonly used Linux commands categorized by their functionality. Each command is accompanied by a brief description of its purpose.

File and Directory Operations

• ls: List directory contents.
• cd: Change directory.
• pwd: Print working directory.
• mkdir: Create directories.
• rmdir: Remove empty directories.
• rm: Remove files and directories.
• cp: Copy files and directories.
• mv: Move/rename files and directories.
• touch: Create empty files or update timestamps.
• ln: Create links between files.
• tree: Display directory tree structure.
• basename: Extract filename from path.
• dirname: Extract directory path.
• realpath: Display absolute path.

File Permissions and Ownership

• chmod: Change file permissions.
• chown: Change file ownership.
• chgrp: Change group ownership.
• umask: Set default permissions.
• sudo: Execute a command as another user.
• su: Switch to another user.
• visudo: Edit sudoers file.
• getfacl: Get file access control lists.
• setfacl: Set file access control lists.

File Searching

• find: Search for files and directories.
• locate: Quickly find files by name.
• which: Display the path to an executable.
• whereis: Locate binary, source, and manual page files.
• grep: Search text using patterns.
• rgrep: Recursively search text in files.
• ag: The Silver Searcher (fast text search).
• ack: Text search tool designed for programmers.

Disk Management

Disk Management

• fdisk: Partition table manipulator.
• gdisk: GUID Partition Table (GPT) partitioning tool.
• parted: Partition manipulation program.
• mkfs: Create a file system.
• mount: Mount a file system.
• umount: Unmount a file system.
• df: Display disk space usage.
• du: Estimate file and directory space usage.
• fsck: File system consistency check.
• badblocks: Check for bad blocks on a disk.
• blkid: Display block device attributes.
• lsblk: List block devices.
• swapon: Enable swap space.
• swapoff: Disable swap space.
• fdisk -l: List all partitions.
• tune2fs: Adjust tunable filesystem parameters.

Process Management

• ps: List running processes.
• top: Display and update sorted information about running processes.
• htop: Interactive process viewer (enhanced top).
• pgrep: Find processes by name or other attributes.
• pkill: Kill processes by name or other attributes.
• kill: Terminate processes by PID.
• killall: Kill processes by name.
• jobs: Display active jobs.
• bg: Put jobs in the background.
• fg: Bring jobs to the foreground.
• nohup: Run commands immune to hangups.
• screen: Terminal multiplexer.
• tmux: Terminal multiplexer.
• at: Execute commands at specified time.
• crontab: Schedule commands to run periodically.

System Information

• uname: Display system information.
• whoami: Display current username.
• who: Show who is logged on.
• w: Show who is logged on and what they are doing.
• id: Display user and group information.
• uptime: Show system uptime and load.
• free: Display memory usage.
• lsb_release: Display Linux Standard Base information.
• lscpu: Display CPU information.
• lshw: List hardware information.
• lspci: List PCI devices.
• lsusb: List USB devices.
• dmidecode: Display system hardware information.
• inxi: Display comprehensive system information.
• neofetch: Display system information with ASCII art.

System Monitoring

• top or htop: Display system and process information.
• vmstat: Virtual memory statistics.
• iostat: Input/output statistics.
• iotop: Monitor I/O usage by processes.
• sar: Collect and report system activity.
• watch: Execute a program periodically.
• dstat: Display system resource statistics.
• glances: Cross-platform system monitoring tool.
• nmon: Performance monitoring tool.
• atop: Advanced system and process monitor.

Memory and Performance

• free: Display memory usage.
• sync: Synchronize cached writes to persistent storage.
• lsof: List open files and processes.
• fuser: Identify processes using files or sockets.
• pmap: Display memory map of processes.
• smem: Memory usage reporting tool.
• valgrind: Memory debugging and profiling tool.

Environment Variables and Shell

• env: Display environment variables.
• export: Set environment variables.
• set: Display or set shell variables.
• unset: Remove variables or functions.
• alias: Create command aliases.
• unalias: Remove command aliases.
• history: Command history.
• which: Show command location.
• type: Display command type.
• echo: Display text.
• printf: Format and print data.
• read: Read input from user.
• source or .: Execute commands from file.

Job Control and Signals

• jobs: List active jobs.
• bg: Move jobs to background.
• fg: Move jobs to foreground.
• disown: Remove jobs from job table.
• kill: Send signals to processes.
• trap: Handle signals in scripts.
• sleep: Delay execution.
• timeout: Run command with time limit.

System Services (systemd)

• systemctl: Control systemd services.
• service: Control system services (SysV).
• systemctl start/stop/restart: Service control.
• systemctl enable/disable: Service autostart.
• systemctl status: Service status.
• journalctl: Query systemd journal.
• systemctl list-units: List systemd units.
• systemctl daemon-reload: Reload systemd configuration.

Text Processing

• cat: Concatenate and display file content.
• less and more: Page through file content.
• head: Display first lines of files.
• tail: Display last lines of files.
• grep: Search text using patterns.
• egrep: Extended grep with regular expressions.
• fgrep: Fast grep for fixed strings.
• sed: Stream editor for text manipulation.
• awk: Text processing and pattern scanning.
• sort: Sort lines in text files.
• uniq: Remove duplicate lines.
• cut: Remove sections from lines.
• tr: Translate or delete characters.
• wc: Word, line, character, and byte count.
• comm: Compare sorted files line by line.
• diff: Compare files line by line.
• patch: Apply differences to files.
• join: Join lines of files on common fields.
• paste: Merge lines of files.
• column: Format input into columns.
• fold: Wrap text to specified width.
• expand: Convert tabs to spaces.
• unexpand: Convert spaces to tabs.

File Transfer and Networking

• scp: Securely copy files between hosts.
• rsync: Synchronize files and directories.
• ftp: File Transfer Protocol client.
• sftp: Secure FTP client.
• ncftp: Improved FTP client.
• curl: Transfer data with URLs.
• wget: Download files from the internet.
• aria2: Multi-protocol download utility.
• rclone: Sync files to cloud storage.

Network Configuration and Troubleshooting

• ping: Send ICMP echo requests.
• ping6: Send ICMPv6 echo requests.
• traceroute: Trace the route to a host.
• tracepath: Trace network path to destination.
• mtr: Network diagnostic tool (traceroute + ping).
• netstat: Display network statistics.
• ss: Display socket statistics (modern netstat).
• dig: DNS lookup utility.
• nslookup: Query DNS records.
• host: DNS lookup tool.
• whois: Query domain registration information.
• ifconfig: Configure network interfaces (legacy).
• ip: Show/manipulate routing, network devices.
• route: Display or modify the routing table.
• arp: Display/modify ARP table.
• ethtool: Display/change Ethernet device settings.
• iwconfig: Configure wireless network interface.
• iwlist: Scan for wireless networks.
• nc (netcat): Network utility for reading/writing network connections.
• telnet: Network protocol client.
• ssh: Secure Shell remote login.

Firewall and Security

• iptables: Configure firewall rules (legacy).
• ip6tables: Configure IPv6 firewall rules.
• ufw: Uncomplicated Firewall management.
• firewall-cmd: Firewall management (firewalld).
• fail2ban: Intrusion prevention framework.
• tcpdump: Capture and analyze network packets.
• wireshark: Network protocol analyzer.
• nmap: Network discovery and security auditing.
• openssl: Cryptography toolkit.
• gpg: GNU Privacy Guard encryption.
• ssh-keygen: Generate SSH key pairs.
• chmod: Change file permissions.
• chattr: Change file attributes.
• lsattr: List file attributes.

Text Editors

• nano: Simple, user-friendly text editor.
• vim or vi: Powerful modal text editor.
• emacs: Extensible, customizable text editor.
• gedit: GNOME graphical text editor.
• kate: KDE advanced text editor.
• sublime-text: Sublime Text editor.
• code: Visual Studio Code.
• micro: Modern terminal-based text editor.
• joe: Easy-to-use text editor.

Archive Management

• tar: Create and extract tar archives.
• gzip: Compress files with gzip.
• gunzip: Decompress gzip files.
• bzip2: Compress files with bzip2.
• bunzip2: Decompress bzip2 files.
• zip: Create zip archives.
• unzip: Extract zip archives.
• rar: Create rar archives.
• unrar: Extract rar archives.
• 7z: Create and extract 7z archives.
• xz: Compress files with LZMA algorithm.
• unxz: Decompress xz files.
• zcat: Display compressed file contents.
• zgrep: Search compressed files.
• compress: Compress files (legacy).
• uncompress: Decompress compressed files.

User Management

• useradd: Add a new user.
• userdel: Delete a user.
• usermod: Modify user settings.
• passwd: Change user password.
• chpasswd: Change passwords in batch.
• groupadd: Add a new group.
• groupdel: Delete a group.
• groupmod: Modify group settings.
• groups: Display groups a user belongs to.
• newgrp: Change current group.
• gpasswd: Administer groups.
• finger: Display user information.
• last: Show last logins.
• lastlog: Show last login times.
• ac: Display user connection time.

Package Management

Debian/Ubuntu (APT)

• apt: Advanced package tool.
• apt-get: Package handling utility.
• apt-cache: Package cache manipulation.
• dpkg: Debian package manager.
• dpkg-query: Query installed packages.

Red Hat/CentOS/Fedora

• yum: Package manager (older systems).
• dnf: Package manager (newer systems).
• rpm: RPM package manager.
• rpm2cpio: Convert RPM to cpio archive.

Other Distributions

• zypper: OpenSUSE package manager.
• pacman: Arch Linux package manager.
• emerge: Gentoo package manager.
• snap: Snap package manager.
• flatpak: Application distribution framework.
• appimage: Portable application format.

System Backup and Restore

• tar: Create and extract backups.
• rsync: Synchronize files and directories.
• dd: Copy and convert files at low level.
• dump: Backup filesystem (ext2/3/4).
• restore: Restore filesystem from dump.
• cpio: Copy files to/from archives.
• rsnapshot: Filesystem snapshot utility.
• borgbackup: Deduplicating backup program.
• timeshift: System restore utility.

System Configuration and Time

• hostname: Display or set system hostname.
• hostnamectl: Control system hostname (systemd).
• date: Display or set system date and time.
• timedatectl: Control system time and date (systemd).
• hwclock: Hardware clock utility.
• ntpdate: Set system time via NTP.
• chrony: NTP client and server.
• locale: Display or set system locale.
• localectl: Control system locale (systemd).
• tzselect: Select timezone interactively.
• shutdown: Shutdown or restart system.
• reboot: Reboot system.
• halt: Halt the system.
• poweroff: Power off the system.
• init: Change system runlevel.

System Logging

• journalctl: Query systemd journal.
• syslog: System log daemon.
• rsyslog: Reliable system log daemon.
• logrotate: Log rotation utility.
• dmesg: Display kernel messages.
• logger: Add entries to system log.
• tail -f: Follow log files in real-time.
• multitail: Monitor multiple log files.

Hardware Information

• lshw: List hardware information.
• lscpu: Display CPU information.
• lspci: List PCI devices.
• lsusb: List USB devices.
• lsblk: List block devices.
• lsmod: List loaded kernel modules.
• modinfo: Display module information.
• modprobe: Load/unload kernel modules.
• rmmod: Remove kernel modules.
• insmod: Insert kernel modules.
• dmidecode: Display hardware information from BIOS.
• hdparm: Hard disk parameters.
• smartctl: Control SMART disk monitoring.
• sensors: Display hardware sensor information.
• acpi: Display ACPI information.

Input/Output and Redirection

• echo: Display text.
• printf: Format and print data.
• cat: Display file contents.
• tee: Write output to file and stdout.
• xargs: Build command lines from input.
• yes: Output a string repeatedly.
• seq: Generate sequences of numbers.
• shuf: Generate random permutations.
• nl: Number lines.
• pr: Format files for printing.

Shell Scripting and Programming

• bash: Bourne Again Shell.
• sh: POSIX shell.
• zsh: Z Shell.
• fish: Friendly Interactive Shell.
• if: Conditional statements.
• for: Loop constructs.
• while: Loop constructs.
• case: Conditional evaluation.
• test or [: Evaluate expressions.
• expr: Evaluate expressions.
• bc: Basic calculator.
• dc: Desk calculator.
• factor: Factor numbers.

File System and Disk Utilities

• fsck: File system check.
• e2fsck: Ext2/3/4 file system check.
• mkfs.ext4: Create ext4 filesystem.
• mkfs.xfs: Create XFS filesystem.
• mkfs.btrfs: Create Btrfs filesystem.
• tune2fs: Adjust ext2/3/4 filesystem parameters.
• resize2fs: Resize ext2/3/4 filesystems.
• xfs_growfs: Grow XFS filesystem.
• btrfs: Btrfs filesystem utilities.
• zfs: ZFS filesystem utilities.

Compression and Encoding

• base64: Base64 encode/decode.
• uuencode: UUencode files.
• uudecode: UUdecode files.
• od: Dump files in octal/hex.
• hexdump: Display file contents in hex.
• xxd: Make hex dump or reverse.
• strings: Extract printable strings.
• file: Determine file type.
• mime-type: Determine MIME type.

Development Tools

• gcc: GNU C compiler.
• g++: GNU C++ compiler.
• make: Build automation tool.
• cmake: Cross-platform build system.
• git: Version control system.
• svn: Subversion version control.
• diff: Compare files.
• patch: Apply patches to files.
• indent: C code formatter.
• ctags: Generate tag files.
• objdump: Display object file information.
• nm: List symbols from object files.
• strip: Remove symbols from object files.
• ldd: Print shared library dependencies.
• strace: Trace system calls.
• ltrace: Trace library calls.
• gdb: GNU debugger.
• valgrind: Memory debugging tool.

Virtual Machines and Containers

• docker: Container platform.
• podman: Daemonless container engine.
• kubectl: Kubernetes command-line tool.
• vagrant: Virtual machine management.
• vboxmanage: VirtualBox command-line interface.
• qemu: Machine emulator and virtualizer.
• virsh: Virtual machine management.
• lxc: Linux containers.

Database Tools

• mysql: MySQL database client.
• psql: PostgreSQL database client.
• sqlite3: SQLite database client.
• mongosh: MongoDB shell.
• redis-cli: Redis command-line interface.

Web and HTTP Tools

• curl: Transfer data with URLs.
• wget: Download files from web.
• httpie: User-friendly HTTP client.
• lynx: Text-based web browser.
• w3m: Text-based web browser.

System Cleanup and Maintenance

• apt autoremove: Remove unnecessary packages (Debian/Ubuntu).
• apt autoclean: Clean package cache (Debian/Ubuntu).
• yum clean: Clean package cache (Red Hat/CentOS).
• bleachbit: System cleaner.
• tmpwatch: Remove old temporary files.
• logrotate: Rotate log files.
• vacuum: Database maintenance.

Miscellaneous Utilities

• cal: Display calendar.
• bc: Basic calculator.
• units: Unit conversion.
• fortune: Display random quotes.
• cowsay: Generate ASCII art of animals.
• figlet: Generate ASCII art text.
• banner: Print large banner text.
• toilet: Generate colored ASCII art.
• sl: Steam locomotive animation.
• cmatrix: Matrix-style terminal screensaver.
• screenfetch: Display system information with ASCII logo.
• hollywood: Fill terminal with Hollywood-style effects.

Please note that this list is not exhaustive, and Linux commands have various options and arguments. It's essential to consult the command's manual page using man <command> for detailed information and usage.

Getting Help

• man: Display manual pages for commands.
• info: Display info documents.
• help: Get help for built-in commands.
• whatis: Display one-line manual page descriptions.
• apropos: Search manual page names and descriptions.
• which: Locate a command.
• type: Display command type and location.
• --help: Most commands support this flag for quick help.

Contribution

We welcome contributions! If you'd like to contribute to this project, please check out our Contribution Guidelines.

Code of Conduct

Please review our Code of Conduct before participating in this project.

License

This project is licensed under the License.

Happy Linux command-line learning!