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## Seven UNIX Commands you can't live without:

If you connect to the Net through a Unix system, eventually you'll have to come to terms with Unix. For better or worse, most Unix systems do NOT shield you from their inner workings -- if you want to copy a Usenet posting to a file, for example, you'll have to use some Unix commands if you ever want to do anything with that file.

Like MS-DOS, Unix is an operating system - it tells the computer how to do things. Now while Unix may have a reputation as being even more complex than MS-DOS, in most cases, a few basic, and simple, commands should be all you'll ever need.

If your own computer uses MS-DOS or PC-DOS, the basic concepts will seem very familiar -- but watch out for the cd command, which works differently enough from the similarly named DOS command that it will drive you crazy. Also, unlike MS-DOS, Unix is case sensitive -- if you type commands or directory names in the wrong case, you'll get an error message.

If you're used to working on a Mac, you'll have to remember that Unix stores files in "directories" rather than "folders." Unix directories are organized like branches on a tree. At the bottom is the "root" directory, with sub-directories branching off that (and sub-directories in turn can have sub-directories). The Mac equivalent of a Unix sub-directory is a folder within another folder.

cat
Equivalent to the MS-DOS "type" command. To pause a file every screen, type cat file |more', better: more file', where "file" is the name of the file you want to see. Hitting control-C will stop the display. You can also use cat' for writing or uploading text files to your name or home directory (similar to the MS-DOS copy con:' command). If you type cat >test' you start a file called "test". You can either write something simple (no editing once you've finished a line and you have to hit return at the end of each line) or upload something into that file using your communications software's ASCII protocol). To close the file, hit control-D.

cd
The "change directory" command. To change from your present directory to another, type cd directory' and hit enter. Unlike MS-DOS, which uses a \ to denote sub-directories (for example: stuff\text), Unix uses a / (for example: stuff/text). So to change from your present directory to the stuff/text sub-directory, you would type cd stuff/text' and then hit enter. As in MS-DOS, you do not need the first backslash if the subdirectory comes off the directory you're already in. To move back up a directory tree, you would type cd ..' followed by enter. Note the space between the cd and the two periods -- this is where MS-DOS users will really go nuts.

cp
Copies a file. The syntax is cp file1 file2' which would copy file1 to file2 (or overwrite file2 with file1).

ls
This command, when followed by enter, tells you what's in the directory, similar to the DOS dir command, except in alphabetical order.

ls |more
will stop the listing every 24 lines -- handy if there are a lot of things in the directory. The basic ls command does not list "hidden" files, such as the .login' file that controls how your system interacts with Unix. To see these files, type ls -a' or ls -a |more'

ls -l' will tell you the size of each file in bytes and tell you when each was created or modified.

mv
Similar to the MS-DOS rename command. In fact, mv file1 file2' will rename file1 as file2, The command can also be used to move files between directories.

mv file1 News' would move file1 to your News directory.

rm
Deletes a file. Type rm filename' and hit enter (but beware: when you hit enter, it's gone for good).

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