Collection of Linux Commands

This document provides a structured list of essential and specialized command-line utilities for Linux, categorized for easier reference and logical function.

GNU Core Utilities (coreutils)

The GNU Core Utilities are the basic file, shell, and text manipulation utilities of the GNU operating system. These tools are expected to exist on every POSIX-like operating system.

File Utilities

These commands are grouped by their primary function: creating, modifying, linking, and managing files and directories.

Creating & Linking

• mktemp: Create a temporary file or directory securely.

• ln: Create links (hard or symbolic) between files.

• mkfifo: Create named pipes (FIFOs).

• mknod: Create special files (block, character, or FIFO).

Copying & Installing

• install: A more feature-rich version of cp, often used in build scripts to set permissions and ownership during installation.

• dd: Convert and copy a file, often used for low-level block-by-block copying.

Modifying Permissions & Attributes

• chmod: Change the access permissions of files.

• chown: Change the user and group ownership of files.

• chgrp: Change the group ownership of files.

• truncate: Shrink or extend the size of a file to a specified size.

Listing

• dir: A variant of ls, lists directory contents.

• vdir: A variant of ls, lists directory contents in a verbose format.

System Operations

• sync: Flush filesystem buffers to disk, synchronizing data.

Text Utilities

These commands are organized from simple viewing and formatting to complex, programmatic text transformation.

Viewing & Basic Formatting

• tac: Concatenate and print files in reverse line order (cat backwards).

• nl: Number the lines of files.

• fmt: A simple text formatter that reformats paragraph text.

• fold: Wrap each input line to fit a specified width.

• od: Dump files in octal and other formats (useful for viewing binary files).

Transforming Content (Characters & Columns)

• tr: Translate or delete characters.

• expand: Convert tabs to spaces in files.

• unexpand: Convert spaces to tabs in files.

• cut: Remove sections (columns) from each line of a file.

• paste: Merge lines of files side-by-side.

Comparing & Combining Files

• comm: Compare two sorted files line by line.

• join: Join lines of two files on a common field.

Splitting Files

• split: Split a file into smaller pieces.

• csplit: Split a file into sections determined by context lines.

Advanced Processing (Stream Editing)

• sed: A stream editor for filtering and transforming text.

• awk: A powerful pattern scanning and processing language. (Note: gawk is the GNU implementation, often symlinked to awk).

Analysis & Indexing

• sum: Print checksum and block counts for a file.

• ptx: Produce a permuted index of file contents.

Shell Utilities

These commands are grouped by their role in providing system information, managing processes, and aiding shell scripting.

Displaying System & User Information

• date: Print or set the system date and time.

• uptime: Tell how long the system has been running.

• nproc: Print the number of processing units available.

• hostid: Print the numeric identifier for the current host.

• who: Show who is logged on.

• users: Print the login names of users currently logged in.

• groups: Print the groups a user is in.

• logname: Print the user's login name.

• tty: Print the filename of the terminal connected to standard input.

• printenv: Print all or part of the environment.

Process & Command Management

• kill: Send a signal to a process (most often to terminate it).

• nice: Run a program with a modified scheduling priority.

• nohup: Run a command immune to hangups, with output to a non-tty.

• timeout: Run a command with a time limit.

• env: Run a program in a modified environment.

• chroot: Run a command or shell in a different root directory.

Scripting & Automation

• echo: Display a line of text.

• printf: Format and print data, similar to the C printf function.

• seq: Print a sequence of numbers.

• yes: Output a string repeatedly until killed.

• sleep: Delay for a specified amount of time.

• test: Check file types and compare values, returning an exit code.

• true: Do nothing, successfully. It always exits with a status code of 0.

• false: Do nothing, unsuccessfully. It always exits with a status code of 1.

• tee: Read from standard input and write to standard output and files simultaneously.

Path & Filename Manipulation

• basename: Strip the directory and suffix from a filename.

• dirname: Strip the non-directory suffix from a filename.

• readlink: Print the value of a symbolic link.

Other Utilities

• expr: Evaluate expressions.

• factor: Print the prime factors of numbers.

• stty: Change and print terminal line settings.

Specialized Command-Line Utilities

This section covers powerful tools that are not part of the standard core utilities and may require separate installation.

Archive and Data Formatting

• unp: A versatile script that unpacks various types of archives. It intelligently handles different formats like .zip, .tar.gz, and .rar, so you don't have to remember the specific extraction command for each.

  • Standard Alternatives: tar, unzip, unrar.

• column: A utility that formats input into well-aligned, multi-column tables, which is very useful for making the output of other commands more readable.

Development Environment Management

• dstack: A specialized tool for provisioning and running development environments. It is not a general-purpose Linux command but is used for managing specific development workflows.

  • Common Alternatives: Vagrant, Docker Compose.