Linux Command Line

The Linux CLI is a text-based interface for interacting with the operating system using commands entered via a terminal emulator, allowing users to perform tasks efficiently without a graphical user interface.

A shell is a program that interprets commands entered into the CLI, processes them, and communicates with the kernel; common shells include Bash (Bourne Again SHell), the default on most distributions.

Use keyboard shortcuts like Ctrl+Alt+T on Ubuntu or search for 'Terminal' in the applications menu; it launches a shell session for command execution.

The pwd (Print Working Directory) command displays the absolute path of the current working directory, helping users confirm their location in the filesystem.

ls lists files and directories; add flags like -l for detailed view, -a to show hidden files, or -h for human-readable sizes.

The cd (Change Directory) command navigates to a different directory; use cd /path for absolute paths, cd .. to go up one level, or cd ~ for home.

The home directory is the user's personal folder, typically /home/username; access it with cd or cd ~.

Use mkdir directory_name to create a single directory or mkdir -p /path/to/nested/dir for parents; it fails if the directory already exists.

touch filename creates an empty file or updates the timestamp of an existing one, useful for initializing files.

cp source destination copies files or directories; use -r for recursive directory copies and -i for interactive prompts.

mv source destination moves files/directories or renames them if destination is in the same directory.

rm file removes files; rm -r dir deletes directories recursively, and -f forces without prompts—use cautiously as deletions are permanent.