Basic Linux Commands used in DevOps

File and Directory Management

• ls: List directory contents.
• cd [directory]: Change the current directory.
• pwd: Print the current working directory.
• mkdir [directory]: Create a new directory.
• rm [file]: Remove a file.
• rm -r [directory]: Remove a directory and its contents recursively.
• cp [source] [destination]: Copy files or directories.
• mv [source] [destination]: Move or rename files or directories.

File Viewing and Editing

• cat [file]: Display file contents.
• more [file]: View file contents one screen at a time.
• less [file]: Similar to more, but allows backward movement in the file.
• nano [file]: Edit a file using the Nano text editor.
• vi [file]: Edit a file using the Vi text editor.

Permissions

• chmod [permissions] [file]: Change the file's permissions.
• chown [user]:[group] [file]: Change file owner and group.

Networking

• ifconfig: Display or configure network interfaces.
• ping [host]: Check connectivity to a host.
• netstat: Display network connections, routing tables, etc.
• curl [url]: Transfer data from or to a server.
• wget [url]: Download files from the web.
• ssh [user]@[host]: Connect to a remote host via SSH.
• scp [file] [user]@[host]:[path]: Securely copy files between hosts.

Process Management

• ps: Display information about running processes.
• top: Display real-time system resource usage.
• kill [PID]: Terminate a process by its Process ID.

Package Management (Debian/Ubuntu)

• apt update: Update the list of available packages.
• apt upgrade: Upgrade installed packages to the latest version.
• apt install [package]: Install a package.
• apt remove [package]: Remove a package.

Disk Usage

• df: Report file system disk space usage.
• du: Estimate file space usage.

System Information

• uname -a: Display all system information.
• hostname: Show or set the system’s host name.
• uptime: Display how long the system has been running.
• free -h: Display available memory and swap usage.

File Search

• find [directory] -name [file]: Search for files in a directory hierarchy.
• grep [pattern] [file]: Search for a pattern in files.

Archiving and Compression

• tar -czvf [archive.tar.gz] [directory]: Create a compressed archive.
• tar -xzvf [archive.tar.gz]: Extract a compressed archive.

User and Group Management

• useradd [username]: Add a new user.
• usermod -aG [group] [username]: Add a user to a group.
• passwd [username]: Change a user's password.

Scheduling and Automation

• crontab -e: Edit cron jobs for scheduling tasks.
• systemctl: Control systemd services.

Logs and Monitoring

• tail -f [file]: Continuously monitor file changes.
• dmesg: Display system boot and diagnostic messages.
• journalctl: Query and display messages from the system journal.