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Essential System Administration, 3rd Edition by Æleen Frisch

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Getting the Most from Common Commands

In this section, we consider advanced and administrative uses of familiar Unix commands.

Getting Help

The manual page facility is the quintessentially Unix approach to online help: superficially minimalist, often obscure, but mostly complete. It’s also easy to use, once you know your way around it.

Undoubtedly, the basics of the man command are familiar: getting help for a command, specifying a specific section, using -k (or apropos) to search for entries for a specific topic, and so on.

There are a couple of man features that I didn’t discover until I’d been working on Unix systems for years (I’d obviously never bothered to run man man). The first is that you can request multiple manual pages within a single man command:

$ man umount fsck newfs

man presents the pages as separate files to the display program, and you can move among them using its normal method (for example, with :n in more).

On FreeBSD, Linux, and Solaris systems, man also has a -a option, which retrieves the specified manual page(s) from every section of the manual. For example, the first command below displays the introductory manual page for every section for which one is available, and the second command displays the manual pages for both the chown command and system call:

$ man -a intro 
$ man -a chown

Manual pages are generally located in a predictable location within the filesystem, often /usr/share/man. You can configure the man command to search multiple man directory trees ...

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