Master Essential Linux Commands for Files and Directories

Linux uses a hierarchical directory tree with the root "/" at the top; other directories are attached via mounting and can be detached by unmounting. Understanding absolute paths (starting with "/") and relative paths (based on the current directory) is essential before using file‑system commands.

Common Directory Commands

ls : list directory contents. Example: ls -al ~ shows all files, including hidden ones, with detailed attributes.

cd : change the current directory. Syntax: cd [absolute|relative path]. Examples demonstrate using absolute paths, relative paths, cd ~ to go home, and cd .. to move up one level.

pwd : print the working directory. Use pwd -P to resolve symbolic links to the real path.

mkdir : create directories. Syntax: mkdir [-mp] directory. Options: -m sets permissions, -p creates parent directories as needed. Example shows creating nested directories with mkdir -p test1/test2/test3/test4 and setting mode 711 to obtain drwx--x--x.

rmdir : remove empty directories. Syntax: rmdir [-p] directory. The -p option removes parent directories if they become empty.

File Copy, Move, and Removal

cp : copy files or directories. Syntax: cp [-adfilprsu] source destination. Options include -a (archive), -r (recursive), -p (preserve attributes), -i (interactive), etc. Example copies .bashrc to /tmp/bashrc with and without prompting.

rm : remove files or directories. Syntax: rm [-fir] target. Options: -f (force), -i (interactive), -r (recursive, dangerous for directories).

mv : move or rename files/directories. Syntax: mv [-fiu] source destination. Demonstrates moving a copied bashrc into a new directory and renaming the directory.

Viewing File Contents

cat : display file from the beginning. Options include -A, -b, -E, -n, -T, -v. Example shows cat /etc/issue.

tac : display file in reverse order (last line first). Example: tac /etc/issue.

nl : number lines with various formatting options ( -b, -n, -w). Example: nl /etc/issue.

more and less : paginate output. Both support navigation keys; less also allows backward scrolling and searching.

head : show the first N lines (default 10). Use head -n 20 file for 20 lines.

tail : show the last N lines (default 10) and can follow a file with -f. Example: tail -n 20 /etc/man.config.

All commands can be explored further with man [command] for detailed documentation.