This cheat sheet includes essential Linux commands and concepts commonly used in the DevOps workflow:

File System Navigation:

• pwd: Print the current working directory.
• ls: List files and directories in the current directory.
  • ls -l: List files and directories in long format.
  • ls -a: List all files and directories, including hidden ones.
• cd: Change the current directory.
  • cd ~: Change to the home directory.
  • cd ..: Move up one directory level.
• touch: Create an empty file.
• mkdir: Create a new directory.
• rm: Remove files or directories.
  • rm -r: Remove directories recursively.
• mv: Move or rename files and directories.
• cp: Copy files and directories.
• find: Search for files and directories.
• grep: Search for text within files.
• cat: Display the contents of a file.
• more or less: View file content page by page.
• head and tail: Display the beginning or end of a file.
• file: Determine file type.

File Permissions:

• chmod: Change file permissions.
• chown: Change file ownership.
• chgrp: Change group ownership.
• umask: Set default permissions for new files and directories.

Process Management:

• ps: List running processes.
  • ps aux: List all processes.
• top: Monitor system processes in real-time.
• kill: Terminate processes.
• killall: Terminate processes by name.
• bg and fg: Manage background and foreground processes.
• nohup: Run a command that continues running even after you log out.

Package Management (Debian/Ubuntu):

• apt-get update: Update package lists.
• apt-get upgrade: Upgrade installed packages.
• apt-get install: Install new packages.
• apt-get remove: Remove packages.
• apt-cache search: Search for packages.
• dpkg: Debian package management commands.

Package Management (Red Hat/CentOS):

• yum update: Update packages.
• yum install: Install packages.
• yum remove: Remove packages.
• yum search: Search for packages.
• rpm: RPM package management commands.

Networking:

• ifconfig or ip: Display network interface information.
• ping: Check network connectivity.
• netstat: Network statistics.
• ssh: Securely access remote systems.
• scp: Securely copy files between systems.
• curl or wget: Download files from the internet.
• nc: Netcat for network-related tasks.
• iptables or firewalld: Configure firewall rules.

System Information:

• uname: Display system information.
• df: Show disk space usage.
• du: Show directory space usage.
• free: Display memory usage.
• top or htop: Monitor system resources.
• lscpu or cat /proc/cpuinfo: CPU information.
• lsblk or fdisk -l: List block devices.
• date: Display the system date and time.

Shell Scripting:

• Create and edit shell scripts using a text editor like nano, vim, or emacs.
• Use #!/bin/bash (or another shell) as the shebang line.
• Make the script executable with chmod +x script.sh.
• Execute the script with ./script.sh.

Version Control:

• git: Git commands for version control.
• svn: Subversion commands for version control.

Containerization (Docker):

• docker: Docker commands for container management.
• docker-compose: Compose multiple containers.

Automation (cron):

• crontab: Schedule recurring tasks.

Text Processing:

• sed: Stream editor for text manipulation.
• awk: Text processing tool.
• cut: Extract sections from lines of files.

Monitoring and Logging:

• Use tools like syslog, journalctl, and logrotate for system logs.
• Use monitoring tools like Nagios, Zabbix, or Prometheus for system health.