Reading UNIX Manual Pages

Use the Terminal app to read the documentation for low-level UNIX tools and APIs.

Overview

The UNIX online manual, known as the man pages, documents low-level UNIX command-line tools, APIs, and file formats. If you’re working at the lowest levels of the system, don’t miss out on this rich source of information.

Display a Man Page in the Terminal App

Type man and the name of a tool or API whose documentation you want to access, and press Return.

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Because the man page is larger than the window, Terminal displays only the first part of the page. Press Space to display subsequent parts, or press Q to exit the man tool.

Search a Specific Section

Section 1 of the man pages covers command-line tools, section 2 covers system calls, section 3 covers user-space libraries, and so on. If you don’t specify a section, man displays the page from the first section that has a matching entry. For example, the following command displays the man page for the open command-line tool.

$ man open

If you want to get the man page for the open system call, specify section 2.

$ man 2 open

If you’re not sure which section to use, do a keyword search using the -k option. For example, the following command shows all the man pages that mention open.

$ man -k open

Learn More About Man Pages

The man command-line tool has its own man page, which is a good place to learn more about this feature.

$ man man