TweetFollow Us on Twitter

Apr 02 Mac OS X

Volume Number: 18 (2002)
Issue Number: 04
Column Tag: Mac OS X

The BSD Man Pages

by Rich Morin

How to find them; how to read them.


"Section 7", the name of this column, is also the shorthand term for the "Miscellaneous Information" section of the Berkeley Software Distribution's manual pages (known to their friends as the BSD "man pages"). This column will feature miscellaneous information on BSD-related aspects of Mac OS X, including application design, documentation, and even the politics of the developer and user communities.

Mac OS X is the most widely-disseminated version of BSD, but many Mac developers are a bit unclear on what BSD actually is. So, a word of explanation may be in order. BSD is a well-respected operating system, with a long history of solid engineering. Derived from Unix 32V, BSD is used for network servers, firewalls, and many other mission-critical applications.

Darwin (and thereby Mac OS X) is based on the FreeBSD and NetBSD distributions. As a result, it can take advantage of a well-developed operating system environment and thousands of "ported" applications from the FreeBSD Ports Collection. Clearly, BSD's solid technology and active developer community make a powerful contribution to the Mac OS X story.

Getting Started

BSD (and other Open Source) developers maintain several thousand "man pages" (manual pages), covering a wide range of topics. Because the pages are written by developers, they tend to be authoritative, consistently organized, current, detailed, and refreshingly honest. On the other hand, they also tend to be terse, tightly focused, and a bit unpolished in spots.

Consequently, reading man pages may not be the best way to approach a new and complex topic (e.g., NFS, socket programming), but it is an extremely handy way to learn about specific commands, remind yourself about forgotten details, etc. Once you've read a few man pages, I predict that you'll get addicted to their strong points; you may even (eventually) forgive their deficiencies.

Although it isn't critically necessary, you'll find it useful (and fun!) to have some Terminal windows on hand while you read this article. For one thing, you'll be able to see the actual output of the commands I'm describing; for another, you'll be able to try things out.

Using the Finder, navigate through the Applications and Utilities folders. When you find the icon for the Terminal Utility, drag it into the Dock. Now, double-click the icon twice, creating two Terminal windows. Unlike typical applications, these windows are not closely tied to each other. In fact, each Terminal window provides an independent BSD "session".

You should probably spend a few seconds arranging the windows, so that you can see them both at the same time. Also, stretch at least one of them vertically (keeping the width constant). This will let you see more of your commands' output without scrolling.

To view a particular man page, you must ask the system to run the "man" command, giving it the name of the page you want to see. We can try this out by asking for the man page that describes the "null" device:

[localhost:~] rdm% man null
NULL(4)         System Programmer's Manual           NULL(4)

     null - the null device

     The null device accepts and reads data as any ordinary
     (and willing) file - but throws it away. The length of
     the null device is always zero.


     A null device appeared in Version 7 AT&T UNIX.


As the example shows, each part of the man page is introduced by a descriptive heading. Some headings (e.g., NAME, DESCRIPTION) will show up on every man page; others (e.g., FILES, HISTORY) only appear when needed. Some, finally, are invented by the page's author. Here are some common headings, in the order they would normally appear on a man page:

  • NAME The following text gives the name(s) of the described item(s), followed by a terse description. In the case of commands, only one name will typically be given. In the case of library functions, however, there may be a long list of entry points.
  • SYNOPSIS The following text gives a (stylized) description of the normal usage mode for the item(s). In the case of commands, this will show the possible option flags; in the case of system calls and library functions, it will show representative declarations, etc.
  • DESCRIPTION The following text gives an extended description of the item(s), including options, usage considerations, etc. Some descriptions go on at great length.
  • RETURN VALUES The following text describes the return values for the item(s).
  • ERRORS The following text lists possible error conditions and resulting actions.
  • FILES The following text lists related files.
  • SEE ALSO The following text lists related man pages.
  • STANDARDS The following text lists applicable standards, sometimes discussing the degree to which the described item(s) comply.
  • BUGS The following text lists ways in which the command fails to meet the documentor's expectations. Some vendors find this section embarassing, so they rename or remove it. Feh!
  • NOTES The following text lists ancillary information which is not appropriate to any of the other sections.
  • HISTORY The following text tells where (i.e., in which BSD or Unix variant) the item first appeared, etc.


With all of this detail, some man pages can (and do :) go on for quite a while. In fact, multiple-page "man pages" are quite common. So, the man command is set up to let the reader "page" through the text. The default "pager" on Mac OS X is "more"; for a rundown on its capabilities, look at its man page!

[localhost:~] rdm% man more

Although more isn't very sophisticated, it does respond to the space bar (skip to the next page), the return key (move forward one line), "q" (quit), and a few other commands. If you want more features, try the GNU Project's "less" command (less is more, more or less):

[localhost:~] rdm% setenv PAGER less


The man pages cover a wide range of topics: administrative and user commands, C language interfaces, devices, etc. If all of the topics were simply sorted together, there would be name clashes. For instance, there is a passwd file, as well as a passwd command. To keep things straight, the man pages are divided into nine sections:

  • Section 1 (General Commands). These are commands that any user might enter from the command line or use in a "shell script". Some example commands include cd, ls, and rm.
  • Section 2 (System Calls). These are C language interfaces to kernel-provided services. Note that a system call, by definition, causes a context switch into the kernel. The application is halted until the system call completes. Some example system calls include close and open.
  • Section 3 (Library Functions). These are also C language interfaces, but the function runs (in general) with the application's context. Of course, some library functions make system calls, which do context switches, as described above. Some example library functions include fopen, scanf, and sqrt.
  • Section 4 (Devices and Device Drivers). These are the external interfaces to system devices. Some devices (e.g., /dev/null, /dev/tty) are intended for direct (command-line) use; others are only accessed by application or system-level code. Consequently, the descriptions in this section vary considerably in level and coverage.
  • Section 5 (File Formats). Many BSD activities are controlled or monitored by means of files. This section describes some of the critical files that an administrator might need to read or edit. Note, however, that Mac OS X uses different administrative mechanisms than most other BSD variants, so your mileage will definitely vary!
  • Section 6 (Games). Some BSD distributions include recreational programs; others do not. By placing these programs in a special area, the operating system eases monitoring and control of their use.
  • Section 7 (Miscellaneous Information). This section includes descriptions that are not tied to any given command, file, or function. Look here for high-level introductions, etc.
  • Section 8 (System Maintenance and Operation Commands). These are commands that the system administrator might enter from the command line or use in a "shell script". Some example commands include chown, fsck, and tunefs.
  • Section 9 (System Kernel Interfaces). These are C language interfaces to kernel-provided services. They differ from system calls in that they can only be called from inside the kernel. Thus, they are only of interest to kernel programmers. Mac OS X does not currently have this section, but FreeBSD does, so I expect it to show up eventually.


Going back to the case of passwd, we see that the passwd command would be described in Section 1, while the passwd file would be described in Section 5. The specific man pages would normally be referred to as "passwd(1)" and "passwd(5)". By default, the man command will display the first page it finds, going in ascending order through the sections. You can make sure that you get passwd(5), however, by typing "man 5 passwd". Try it!

Unlike the hierarchical "help systems", as found on Cicso routers or operating systems such as VMS, man pages have no automated support for navigation. Some experimental variants use HTML to display man pages, turning SEE ALSO entries into hyperlinks. Most man systems, however, require that you do your own navigation.

Part of the reason for this lies in the sheer scale of the BSD command set. There are several hundred commands and thousands of functions. Trying to place them all in a meaningful hierarchy (or even defensible topical groupings) is not a trivial task! Nonetheless, some help is available.

To find a man page when you don't know the exact name, use apropos(1). It displays all the "NAME" lines that contain the specified text strings. If you are trying for a text string that contains non-alphanumeric characters, be sure to enclose the string in quotes. Otherwise, you'll get all the pages that match any "word" (i.e., sequence of non-blank characters) in the string. Here are some interesting uses of the apropos command; try them out!

[localhost:~] rdm% apropos device
[localhost:~] rdm% apropos dev
[localhost:~] rdm% apropos ‘(4)'
[localhost:~] rdm% apropos ‘file system'
[localhost:~] rdm% apropos file system

Although BSD provides several hundred commands, only a few are needed for everyday use. Next month, we'll look at some basic BSD commands, as well as a smattering of shell (command line interface) syntax.

Rich Morin has been using computers since 1970, Unix since 1983, and Mac-based Unix since 1985 (when he helped Apple create A/UX 1.0). When he isn't writing this column, Rich runs Prime Time Freeware (, a publisher of books and CD-ROMs for the Free and Open Source software community. Feel free to write to Rich at


Community Search:
MacTech Search:

Software Updates via MacUpdate

Microsoft Office 2016 16.11 - Popular pr...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook, and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
Adobe Photoshop CC 2018 19.1.2 - Profess...
Photoshop CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Photoshop customer). Adobe Photoshop CC 2018, the industry standard... Read more
Adobe Dreamweaver CC 2018 -...
Dreamweaver CC 2018 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Dreamweaver customer). Adobe Dreamweaver CC 2018 allows you to... Read more
Adobe Flash Player - Plug-in...
Adobe Flash Player is a cross-platform, browser-based application runtime that provides uncompromised viewing of expressive applications, content, and videos across browsers and operating systems.... Read more
Drive Genius 5.2.0 - $79.00
Drive Genius features a comprehensive Malware Scan. Automate your malware protection. Protect your investment from any threat. The Malware Scan is part of the automated DrivePulse utility. DrivePulse... Read more
MegaSeg 6.0.6 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
ffWorks 1.0.7 - Convert multimedia files...
ffWorks (was iFFmpeg), focused on simplicity, brings a fresh approach to the use of FFmpeg, allowing you to create ultra-high-quality movies without the need to write a single line of code on the... Read more
Dash 4.1.5 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Evernote 7.0.3 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
jAlbum Pro 15.3 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Oh hi nice reader, and thanks for popping in to check out our weekly round-up of all the stuff that you might have missed across the Steel Media network. Yeah, that's right, it's a big ol' network. Obviously 148Apps is the best, but there are some... | Read more »
All the best games on sale for iPhone an...
It might not have been the greatest week for new releases on the App Store, but don't let that get you down, because there are some truly incredible games on sale for iPhone and iPad right now. Seriously, you could buy anything on this list and I... | Read more »
Everything You Need to Know About The Fo...
In just over a week, Epic Games has made a flurry of announcements. First, they revealed that Fortnite—their ultra-popular PUBG competitor—is coming to mobile. This was followed by brief sign-up period for interested beta testers before sending out... | Read more »
The best games that came out for iPhone...
It's not been the best week for games on the App Store. There are a few decent ones here and there, but nothing that's really going to make you throw down what you're doing and run to the nearest WiFi hotspot in order to download it. That's not to... | Read more »
Death Coming (Games)
Death Coming Device: iOS Universal Category: Games Price: $1.99, Version: (iTunes) Description: --- Background Story ---You Died. Pure and simple, but death was not the end. You have become an agent of Death: a... | Read more »
Hints, tips, and tricks for Empires and...
Empires and Puzzles is a slick match-stuff RPG that mixes in a bunch of city-building aspects to keep things fresh. And it's currently the Game of the Day over on the App Store. So, if you're picking it up for the first time today, we thought it'd... | Read more »
What You Need to Know About Sam Barlow’s...
Sam Barlow’s follow up to Her Story is #WarGames, an interactive video series that reimagines the 1983 film WarGames in a more present day context. It’s not exactly a game, but it’s definitely still interesting. Here are the top things you should... | Read more »
Pixel Plex Guide - How to Build Better T...
Pixel Plex is the latest city builder that has come to the App Store, and it takes a pretty different tact than the ones that came before it. Instead of being in charge of your own city by yourself, you have to work together with other players to... | Read more »
Fortnite Will Be Better Than PUBG on Mob...
Before last week, if you asked me which game I prefer between Fortnite Battle Royale and PlayerUnknown’s Battlegrounds (PUBG), I’d choose the latter just about 100% of the time. Now that we know that both games are primed to hit our mobile screens... | Read more »
Siege of Dragonspear (Games)
Siege of Dragonspear 2.5.12 Device: iOS Universal Category: Games Price: $9.99, Version: 2.5.12 (iTunes) Description: Experience the Siege of Dragonspear, an epic Baldur’s Gate tale, filled with with intrigue, magic, and monsters.... | Read more »

Price Scanner via

Sunday Sales: $200 off 13″ Touch Bar MacBook...
Amazon has new 2017 13″ 3.1GHz Touch Bar MacBook Pros on sale this weekend for $200 off MSRP, each including free shipping: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (MPXV2LL/A): $1599.99 $200 off... Read more
B&H drops prices on 15″ MacBook Pros up t...
B&H Photo has dropped prices on new 2017 15″ MacBook Pros, now up to $300 off MSRP and matching Adorama’s price drop yesterday. Shipping is free, and B&H charges sales tax for NY & NJ... Read more
Apple restocks Certified Refurbished 2017 13″...
Apple has restocked Certified Refurbished 2017 13″ 2.3GHz MacBook Pros for $200-$230 off MSRP. A standard Apple one-year warranty is included with each MacBook, models receive new outer cases, and... Read more
13″ Space Gray Touch Bar MacBook Pros on sale...
Adorama has new 2017 13″ Space Gray Touch Bar MacBook Pros on sale for $150 off MSRP. Shipping is free, and Adorama charges sales tax in NY & NJ only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (... Read more
Best deal of the year on 15″ Apple MacBook Pr...
Adorama has New 2017 15″ MacBook Pros on sale for up to $300 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $... Read more
Save $100-$150+ on 13″ Touch Bar MacBook Pros...
B&H Photo has 13″ Touch Bar MacBook Pros on sale for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 3.1GHz/256GB Space Gray MacBook Pro... Read more
Current deals on 27″ Apple iMacs, models up t...
B&H Photo has 27″ iMacs on sale for up to $150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2149 $150 off MSRP – 27″ 3... Read more
Thursday Deal: 13″ 2.3GHz MacBook Pro for $11...
B&H Photo has the 13″ 2.3GHz/128GB Space Gray MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz/128GB Space... Read more
How to save $100-$190 on 10″ & 12″ iPad P...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
Silver 12″ 1.3GHz MacBook on sale at B&H...
B&H Photo has the 2017 12″ 1.3GHz Silver MacBook on sale for $1399.99 including free shipping plus sales tax for NY & NJ residents only. Their price is $200 off MSRP, and it’s the lowest... Read more

Jobs Board

Firmware Engineer - *Apple* Accessories - A...
# Firmware Engineer - Apple Accessories Job Number: 113452350 Santa Clara Valley, California, United States Posted: 28-Feb-2018 Weekly Hours: 40.00 **Job Summary** Read more
Automation and Performance Engineer, *Apple*...
# Automation and Performance Engineer, Apple Pay Job Number: 113557967 Santa Clara Valley, California, United States Posted: 09-Mar-2018 Weekly Hours: 40.00 **Job Read more
Hardware Systems Architect - *Apple* Watch...
# Hardware Systems Architect - Apple Watch Job Number: 113565323 Santa Clara Valley, California, United States Posted: 05-Mar-2018 Weekly Hours: 40.00 **Job Read more
Lead *Apple* Solution Consultant - Apple (U...
# Lead Apple Solution Consultant Chicago IL Job Number: 113560644 Chicago, Illinois, United States Posted: 10-Mar-2018 Weekly Hours: 40.00 **Job Summary** As a Lead Read more
Art Director, *Apple* Music + Beats1 Market...
# Art Director, Apple Music + Beats1 Marketing Design Job Number: 113258081 Culver City, California, United States Posted: 07-Mar-2018 Weekly Hours: 40.00 **Job Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.