UNIX - Basic Commands

The basic form of any UNIX command is:
command_name options argument(s)

Unix is case-sensitive.
Unix distinguishes between upper and lower case letters in the names of files and programs. Thus, while ls is a valid Unix command, LS is not.
Login names and passwords are also case-sensitive.
A filename in Unix can consist of any combination of characters on the keyboard except for the space bar and all of the following : * ? ! \ \ ‘ “ > ;, ^ ( ) $ ~. These characters cannot be used in filenames because they have special meaning to the shell. For instance, the first two characters are used as “wildcards”.
Some programs, such as Pico, have their own commands that you type within the program rather than at the Unix shell prompt. The Shell prompt reappears whenever you exit those programs.
If by any means any of your commands do not work, than please visit the following websites.
- Fixing Lost UNIX Commands W/ Pico
- Fixing Lost UNIX Commands W/ VI

File and Directory Handling Commands

ls: Lists your files
ls –l: Lists your files in ‘long format’, which information such as the exact size of the file, who owns the file, who has the right to look at it, and when was it last modified.
ls –a: List all the files, including the ones whose filenames begin in a dot, which you do not always want to see.
mv file1 file2: Moves a file into a different directory, or renames the file.
cp file1 file2: Copies a file
rm filename: Removes a file. Preferably use rm –i which will ask you for confirmation before deleting the file
wc filename: Tells you how many lines, words, and characters there are in a file
chmod option file: Lets you change the read, write, and execute permissions on your files. chmod o+r filename will make the file readable for everyone, and chmod o-r filename will make it unreadable for others.
mkdir dirname: Make a new directory
cd dirname: Change directory. You can basically go to another directory and can view the files in that directory
pwd: Tells you which directory you are currently browsing.

lpr filename: Print. Use the –P command to specify for the printer name. For printing in TAMU CS Department, please refer below.
lpq: Check out the printer queue. This can be used to get the number needed for removal, or to see how many other files will be printed before yours can come out
lprm jobnumber: Remove a job from the printer queue. As mentioned above, you can find the job number using lpq.
To print Duplex: type
ppr-Pps210 -twosided filename

whoami: Returns your username. This command can be used to find out if someone is already logged on and had forgotten to log out.
ps –u yourusername: Lists your processes. Contains information such as the process ID, which you might need to kill a particular process which would be creating difficulties on your computer
kill processID: Ends the process, whose process ID you typed in.
quota –v OR zquota: Show what your disk quota is, how much you’re using, and incase you have exceeded your quota.
du filename: Shows the disk usage of the files and the directories in filename, du –sk will give a total of all files and directories on the disk
last yourusername: Lists your last logins.
finger username: Gives you lots of information about that user, e.g. when they last read their mail and whether they’re logged in.
w: Tells you who’s logged in, and what they’re doing.
who: Tells you who’s logged on, and which computer they are logged on to..
last –1 username: Tells you when the user last logged on and off and from where.
talk username: Lets you have a typed conversation with another user (primitive chat service)
write username: Lets you exchange one line messages with another user (primitive chat service)

mail: By typing this into your Unix shell prompt it will give you a list of mail on your account. All you need to do is type in the mail number on the mail prompt and it will open up
pine: Basically the same function as the mail command, but with a better user interface
rlogin hostname: Lets you connect to a remote host
telnet hostname: Lets you connect to a remote host. Use rlogin whenever possible
ftp hostname: Lets you download files from a remote host which is set up as an ftp-server
The commands mail and pine(see pine handout) are programs that run to check your mail and thus they will have their own commands and ways to maneuver inside. A hostname will look something like a web address (e.g. unix.tamu.edu).

date: Shows the current date and time
cal: Shows a calendar of the current month. If you type in cal 10 1995 you will get the calendar for the moth of October in the year 1995.
man commandname: Shows you the manual page for the command
clear OR Ctrl + l: Refreshes or clears your screen.
Ctrl + c: Stops running program or the command
Ctrl + p: Retrives the last shell command you typed
Ctrl + z: Suspends the currently running program or command
exit: Ends your SSH session.