Essential Linux Command-Line Tools Every Developer Should Know

lsb_release

A utility for querying Linux distribution information, showing details defined by the Linux Standard Base (LSB). Common options include:

-a: display all available information (ID, description, version, codename)

-d: show only the description

-r: show only the release number

-c: show only the codename

-v: display LSB version in a module‑description list

-s: output in a concise format suitable for scripts

-h: show help

pwd

Print Working Directory – displays the absolute path of the current directory.

ls

Lists directory contents. Frequently used options:

-a: include hidden files (those beginning with a dot)

-l: long format showing permissions, owner, size, etc.

-al: combine -a and -l for a detailed view of all files

Example output fields are explained (permissions, link count, owner, group, size, modification date, filename).

clear

Clears the terminal screen; the same effect can be achieved with Ctrl+L.

touch

Creates an empty file or updates the timestamps of an existing file. touch longxia.txt If the file does not exist, a zero‑byte file is created; if it exists, its access and modification times are refreshed without altering content.

vi

A powerful text editor with three primary modes:

Command mode – cursor movement, text deletion, copy/paste, mode switching

Insert mode – entered with i/a/o to insert text before, after, or on a new line

Ex commands – e.g., :w to save, :q to quit, :q! to quit without saving, :wq to save and quit

Esc returns to command mode.

cp

Copies files or directories.

cp source_file target_file

cp -r source_dir target_dir (recursive copy)

cp -p source_file target_file (preserve attributes such as timestamps and permissions)

mkdir

Creates directories.

-p: create parent directories as needed; ignore if the directory already exists

-m mode : set directory permissions explicitly (e.g., mkdir -m 750 private)

-v: verbose output showing each created directory

mv

Moves or renames files and directories. Frequently used options:

-i: interactive, prompt before overwriting

-f: force overwrite without prompting

-n: never overwrite existing files

-v: verbose, show each rename operation

-u: overwrite only when the source is newer

-t dir : move multiple files into the specified target directory

cd

Changes the current working directory. Useful shortcuts:

~: home directory

..: parent directory

/: root of the filesystem

rm

Removes files or directories.

-f: force removal, ignore nonexistent files

-i: interactive, ask before each deletion

-r: recursive removal of directories and their contents

-v: verbose, display each removal

-d: remove empty directories only

history

Manages the command history.

-c: clear the current session’s history (in memory only)

-d n : delete the entry at line number n

-w: write the in‑memory history to .bash_history -a: append new commands to .bash_history -r: read and merge the history file back into the session

df

Displays filesystem disk space usage.

-h: human‑readable sizes (e.g., 124K, 345M)

-i: show inode information instead of block usage

-T: display filesystem type

-k: show sizes in 1024‑byte blocks

cat

Concatenates and prints file contents. Common uses:

Display a file: cat myFile.txt Create a file: cat > newfile.txt Merge files: cat file1.txt file2.txt > combined.txt Append to a file: cat file2.txt >> file1.txt Useful options:

-n: number all lines (including blanks)

-b: number non‑blank lines only

-A: show all control characters

-e: display $ at end of each line

-t: display tabs as ^I

-v: show non‑printing characters

less

A pager for viewing file contents with navigation, search, and line‑number display.

less log.txt

less -i file.txt   # ignore case in searches

/error   # search forward for "error"

?warning # search backward for "warning"

n        # repeat previous search forward

N        # repeat previous search backward

type

Shows how the shell would interpret a command (builtin, alias, file, etc.). Options:

-p: display the full path of external commands

-a: list all possible definitions

whoami

Prints the effective username of the current user.

which

Locates the executable file associated with a command by searching the directories in $PATH.

-a: show all matching paths

-V: display version information

man

Displays the manual page for a command or topic. man ls: view the manual for

ls

man -k keyword

: search manual page names and descriptions for a keyword

alias

Creates a shortcut name for a command or series of commands (e.g., alias ll='ls -l'). The alias is only valid for the current shell session.

sort

Sorts lines of text files.

-n: numeric sort

-r: reverse order

-f: ignore case

-t sep : use sep as field delimiter (e.g., -t ',')

-k pos : sort by the specified field

grep

Searches files for lines matching a regular expression.

-c: count matching lines

-n: show line numbers

-i: ignore case

-v: invert match (show non‑matching lines)

wc

Counts bytes, words, and lines in a file.

-c: byte count

-l: line count

-w: word count

head

Shows the beginning of a file (default first 10 lines).

-n NUM : display the first NUM lines

-c NUM : display the first NUM bytes

-q: suppress file name headers

-v: always show file name headers

tail

Shows the end of a file (default last 10 lines) and can follow file growth.

-n NUM : display the last NUM lines

-c NUM : display the last NUM bytes

-f: follow the file as it grows

-q: suppress headers

-v: always show headers