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basic unix commands

There's more to your e-mail account than just reading your mail!

Bracketed information [] is used in conjunction with the command -- read the first command, man for further explanation.

C$ man [-k topic]
Man displays short manual pages for many commands and programs installed on the UNIX system. The [-k topic] in brackets indicates that this information may be used with the command man. You can either type man command, where command is the command you want information on; or you can use the format man -k topic, where topic is the keyword of the general subject you want information on. Now that you know the man command, you can look up the manual entries (called "man pages") on any UNIX command you need to find out about.

C$ more [filename]
More displays a text file, one screen at a time. Type more file_1 to see the text file named file_1. More is roughly the equivalent of the DOS command "type".

C$ who
Who lists all the users logged onto wjh. Finger will also list all the users logged onto wjh.

C$ finger [username]
Shows the finger information and last login of a certain user. Using the finger command without a certain username will just show all users logged on at present. To show finger info one screen at a time, type finger [username] | more

C$ write [username]
Sends a message directly to the user specified. Useful if you want to get someone's attention who's logged on. (Beware, though, some people are very irritated by write messages...) To end the write session, hit control-D.

C$ talk [username]
Requests an interactive 'talk' session with the other user. If they accept your talk request, the screen divides in two and both of you can write at the same time. To exit a talk session, hit control-C.

C$ mesg [n] [y]
Allows or disallows interruptive messages, such as talk or write. To deny all write and talk messages, use the command mesg n. To allow write/talk access, mesg y.

C$ w
w lists what all the users logged in are doing. A typical 'w' listing might look like this:

 3:55pm  up 7 days, 12:45,  3 users,  load average: 0.27, 0.57, 0.37
User     tty from          login@   idle   JCPU   PCPU  what
cindy    p0     3:13pm     5      1      1  telnet fas
cindy    p1 destiny.harvar  3:36pm                      w
kemo     p4 mabaker.studen 10:19am           14         pine help

w means that other users can see what processes you are running, and you can see what processes they are running. UNIX is a very public operating system.

C$ last [username]
Shows a log of the most recent logins of a certain user. You can also look up the last n times a user has logged on with: last -n [username]

C$ cd [directory]
cd changes the directory you're in. When you log in, you're automatically in your home directory on wjh. Your home directory might contain several directories, like

Mail           News              WWW
To go up a level in the directory hierarchy, type cd .. or you can use the command pwd to give your present working directory.

C$ ls
Lists the files in your home directory.

Some files are 'invisible.' For example, if you use the e-mail program Pine you will have an invisible file called .pinerc with your configuration settings. To show all of these files, you can use the command ls -a. To show all files, type ls -al.

C$ cp [filename] [directory]
Copies a file into a directory. For example, to save my_file into my_directory:
C$ cp my_file my_directory

C$ mv
The mv command moves a file into a new file; in essence it just renames your files.
C$ mv old-name_file new-name_file
will replace the file old-name_file with a file named new-name_file. Files can also be moved to different directories with the mv command.
C$ mv file_name new_folder
will move the file File_name into a directory called new_folder.

C$ cal
Will give a small calendar. The command cal by itself gives the calendar for the current month and year, or you can specify another month and/or year.

C$ cal 8 1995
   August 1995
 S  M  Tu  W  Th  F  S
       1   2   3  4  5
 6  7  8   9 10  11 12
13 14 15 16  17  18 19
20 21 22 23  24  25 26
27 28 29 30  31

C$ frm
The frm command tells who your e-mail is from and also lists the subject lines. This only shows messages currently in your inbox. To find out who your new mail only is from, you can use the command nfrm.

C$ chmod
Chmod is a command that should be used carefully. It is used to change the permissions on files, that is, you can make your files world-readable or limit all access to yourself. For example, your e-mail directory is defaulted to be read only by you, the user. However, directories that contain web files must be world-executable.

C$ rm
Removes (deletes) a file. To remove a directory, type rmdir directory_name. Directories must be empty before being deleted.

C$ alias
Allows you to set a command equal to an easier-to-type alias.
C$ alias p pine

will set the command pine equal to p. However, this alias will only work during this session; once you log out the alias will no longer work.

C$ mail
Mail is a very un-friendly e-mail program. I'd recommend sticking with pine. However, you can send files easily with mail by typing
C$ mail jschmoe@wjh.harvard.edu < filename

You can also get help on additional commands at C.C. Taylor's site at the IEEE.

William James Hall Computer Services

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Last modified Mar 31, 1998, 17:28:29 EST