Common Commands

In any UNIX environment, there are certain commands a user needs to know to be able to easily manipulate files, and manage their account.

The most important command in UNIX is the man command. This is the command that gives you access to the system documentation. It provides you with the proper syntax for any command. For more information about man, tpye “man man” at the UNIX prompt.

Below is a list of the most common UNIX commands. You may also type “man <command>” at a terminal prompt to access the man page of the command. This will provide you the the Syntax of the command.

Commands that deal with the placement, modificaiton and removal of files in a user's account. This section does not discuss editors.

cat
The cat command is used to concatenate and display files to the screen, or optionally to some other destination. Cat is useful when you want to combine two or more files together into one file.|

more
The more command is used to page through files page by page so you can easily read it.

less
The less command is used page through files page by page. You can also move backward.

cp
cp is the copy command. It is used for copying a file or files from one location to another. It is functionally similar to the DOS copy command.

rm
rm is the remove command. It is used for deleting, or removing a file or files from one or more locations. Becareful what files you delete, in some cases they may be unrecoverable, even by PCN staff.

mv
mv is the move command. It is used for moving files to a different location. It is also funcionally similar to the DOS move command. Single files can also be renamed using this command.

mkdir, rmdir
mkdir and rmdir are the commands used to make a directory, or to remove a directory. Note: rmdir can only remove a directory when there is nothing left inside it.

chmod
chmod changes the mode of the file or files it is acting upon. There are two methods for changing the modes of files, absolute and symbollic. Both are widely accepted. Note that directories must have their modes always set executable, or they cannot be accessed.

Progams that are used to find information about a user, or to communicate with another user. This list does not discuss E-Mail.

finger
finger is a command that displays information about other users. A user has the ability to modify this information to some extent.

who
who is a command that tells the user what other users are logged into a particular machine.

write
The write command sends a one way message to a user that is logged in. This command is useually only appropriate for short messages that are expedient in nature.

talk
The talk command sends a request to a user that is logged in to begin a talk session. Talk is a real-time two way communication method. It is most commonly used in situations where one way multiple writes become annoying.

These commands may or may not be available on all UNIX systems, but should be available to any PCN user.

date
The date command tells the user the current day of the week, month, day, time, timezone, and year.

uptime
uptime tells the user how long the machine has been functioning properly since its last shutdown ( scheduled or otherwise ), and also tells the number of users and system load average. This information is of little use to the casual user.

quota
The quota command when executed as:

quota -v

gives the user a list of how much disk space he or she has used, and how much space he may use. The limit field is known as the hard limit. The user make utilize disk space up to his hard limit, but after a set time there will be a restriction placed on the user's account until usage has been reduced to below the quota field's number (called the soft limit).

weather
The weather command displays the current local weather and the forecast for the days to come.