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$ scp logfiles/temp_junk mdw@eggplant:

Once again, the username and @ can be omitted if it's the same on both systems. (But the -l syntax doesn't work on scp; it uses a different -l option for a different purpose.)

Be sure to include the final colon; without it, you simply copy the file to a new file named eggplant on your local system. On eggplant, the default directory is your home directory (as with ssh). You can specify that the file be copied to any directory you have access to, with a path relative to the home directory or with an absolute pathname.

To do the reverse operation—copy a file from the remote system to your own—enter:

$ scp mdw@eggplant:logfiles/temp_junk .

We used a single dot here to denote the local directory where you're executing the command. Any relative or absolute pathname could be specified instead.

To copy a directory, add the -r option:

$ scp -r mdw@eggplant:logfiles .

Manual Pages

The most empowering information you can get is how to conduct your own research. Following this precept, we'll now tell you about the online help system that comes built into Unix systems. It is called manual pages , or manpages for short.

Actually, manual pages are not quite the boon they ought to be. This is because they are short and take a lot of Unix background for granted. Each one focuses on a particular command and rarely helps you decide why you should use that command. Still, they are critical. Commands can vary slightly on different Unix systems, and the manual pages are the most reliable way to find out what your system does. (The Linux Documentation Project deserves a lot of credit for the incredible number of hours they have put into creating manual pages.) To find out about a command, enter a command, such as the following:

$ man ls

Manual pages are divided into different sections depending on their purpose. User commands are in section 1, Unix system calls in section 2, and so on. The sections that will interest you most are 1, 5 (file formats), and 8 (system administration commands). When you view manpages online, the section numbers are conceptual; you can optionally specify them when searching for a command:

$ man 1 ls

But if you consult a hardcopy manual, you'll find it divided into actual sections according to the numbering scheme. Sometimes an entry in two different sections can have the same name. (For instance, chmod is both a command and a system call.) So you will sometimes see the name of a manual page followed by the section number in parentheses, as in ls(1).

There is one situation in which you will need the section number on the command line: when there are several manual pages for the same keyword (e.g., one for a command with that name and one for a system function with the same name). Suppose you want to look up a library call, but the man command shows you the command because its default search order looks for the command first. In order to see the manual page for the library call, you need to give its section number.

Look near the top of a manual page. The first heading is NAME. Under it is a brief one-line description of the item. These descriptions can be valuable if you're not quite sure what you're looking for. Think of a word related to what you want, and specify it in an apropos command:

$ apropos edit

The previous command shows all the manual pages that have something to do with editing. It's a very simple algorithm: apropos simply prints out all the NAME lines that contain the string you request.

Many other utilities, particularly those offered by the desktops discussed in Chapter 3, present manual pages attractively.

Like commands, manual pages are sometimes installed in strange places. For instance, you may install some site-specific programs in the directory /usr/local, and put their manual pages in /usr/local/man. The man command will not automatically look in /usr/local/man, so when you ask for a manual page you may get the message