UNIX Commands

UNIX COMMANDS

Where to Get More Information

This summary of UNIX commands provides a brief introduction which will help get you started with SAS on UNIX. For more information, you can check the links listed below.

Account Activation Select the "Activating ..." link.

Disk Quota This site contains a link for requesting a quota increase. (If it doesn't work, try the network page)

Change shell The first screen is the same as for disk quota. Select "Change your UNIX Login Shell." Then select the t-shell (/bin/tcsh). And be sure to logout when finished.

The T-shell supports use of arrow keys to recall and edit commands. The default C-shell (/bin/csh) does not.

Password Reset The first screen is a logon screen. This site contains several other links to system utilities. Be sure to logout when finished.

Unix Tips

Also, if you know the name of a UNIX command you can use the UNIX man command (man stands for manual). For example, to find out more about the UNIX copy command, called cp, type --

man cp

The result is a detailed description of the cp command. The descriptions sometimes are technical, however.

Features of UNIX

Unlike the Windows operating system, UNIX commands are typed at the prompt of a terminal window. Typing comands may seem awkward at first, but it often is much quicker to execute commands from a command prompt than with a window environment. The prompt for the UNIX machine named strauss is --

strauss.udel.edu%

althought this may vary, and can be customized.

UNIX file names may contain as many as 255 characters, but most file names contain two parts, a root consisting of a few to several characters followed by an extension consisting of up to eight characters, although these conventions often are violated. The root and extension are separated by a period - root.ext. UNIX file names are case sensitive. So, for example, contents.sas is not the same as CONTENTS.SAS.

The UNIX file system is hierarchical, similar to Windows. Individual files are placed in directories, often called folders. Directory names consist of paths, with each subdirectory separated from the others in a path by a forward slash, for example -

~/sasclass

indicates a directory named sasclass. The directory sasclass is a subdirectory of the user's home directory (the ~/ is a shorthand notation for the complete path defining your home directory, in this example - /home/usra/7d/32007/). UNIX directory paths contain no drive letters.

Type UNIX commands at the UNIX prompt. UNIX commands also are case sensitive. So, for example, ls is not the same as LS.

UNIX Exercise

Some useful/essential UNIX commands for statistical work are given in the UNIX exercises.

UNIX commands

Type the text in the blue boxes at the UNIX prompt.

quota -v - check quota: example --

     quota -v

This command returns a summary of your UNIX disk quota which looks something like --

Disk quotas for traing (uid 16558):
Filesystem     usage  quota  limit    timeleft  files  quota  limit    timeleft
/home/usra      5128  10240  10240                532  76800  76800            
/home/kodos/vol0
               30680 204800 204800                  1  76800  76800

To request more disk quota, go to the the network page

ls - list files, you can use the asterisk character (*) as a "wildcard", example --
```
     ls
     ls ~larryh/sasintro/*.sas
```
Note that the second line produces a list of all the files in a subdirectory of my home directory with an extension of .sas. The tilde ~ before a username stands for the user's home directory.
mkdir directory - make a new directory called directory, example --
```
     mkdir sasclass
```
If it executes correctly, you get no reply from the mkdir command.
cd directory - change directory to directory, example --
```
     cd sasclass
```
If it executes correctly, you get no reply from the cd command.
pwd - print working directory, example --
```
     pwd
```
The pwd command returns the full pathname of your current directory, for example --
```
/home/usra/7d/32007/sasclass
```
The cd command with no directory name brings you back to your home directory. Try this, then type pwd to see the name of your home directory. Then change directory back to sasclass. Here is the sequence --
```
     cd
     pwd
     cd sasclass
     pwd
```
If it executes correctly, you get no reply from the two cd commands. You should get something analogous to --
```
     /home/usra/7d/32007
```
to the first pwd command and something like --
```
/home/usra/7d/32007/sasclass
```
in response to the second pwd command.
cp oldfile newfile -- copy oldfile to newfile, example --
```
     cp ~larryh/sasnotes/contents.sas .
```
This command copies the file in the ~larryh/sasclass directory called contents.sas into your current working directory (sasclass). Note: The period at the end indicates to use the same filename as the original filename. Either a period or a file name is a required part of the syntax.
pico filename - start the pico editor to edit filename, example --
```
     pico contents.sas
```
The pico screen shows most of the key commands at the bottom. Exit pico by pressing ^X.
mv oldfile newfile - move/rename oldfile to newfile, example -
```
     mv contents.sas cont.sas
     ls
     mv cont.sas contents.sas
     ls
```
You get no response from the mv commands. You should get --
```
     cont.sas 
```
from the first ls command and --
```
     contents.sas
```
from the second.
cat file - type file to your screen (more than one file may be listed), example --
```
     cat contents.sas
```
This is a short file and displays easily on one screen. You should see --
```
  options linesize=80 noovp;
  libname lhsas '~larryh/sasnotes';

    proc contents data=lhsas.gss04; run;
```
But the cat command is useful primarily for short files.

more file - view a file, stopping each time the screen fills, with capacity to go forward a line or a screen at a time, and back a screen at a time, example --

     more ~larryh/sasnotes/dataprep.sas

This file ( ~larryh/sasnotes/dataprep.sas) contains more lines than one terminal screen. While viewing it with more, use --

	<SPACEBAR>	go down a full screen
	b	go back a full screen
	, j	go down one line
	/string	search forward for string
	?	for help
	q	for quit before the end of the file

Note: more automatically exits at the end of the file. To get another pager program that does not, and has other useful features, use less instead of more (see below).

diff file1 file2 -- compare file1 to file2 for differences, example --
```
     cp contents.sas abc
     cat contents.sas abc
     diff contents.sas abc
```
You get no response from the cp command. The cat command is used to list the files to the screen so you can see they are the same. The diff command returns no response. Only if the files being compared differ does diff return a reply. The reply is cryptic (code for changing one file so it matches the other). As a beginner, use it as an indicator that the files are different.
rm file -- remove file, example --
```
     rm abc
     ls abc
```
If your account is set up correctly, the rm command reponds by asking you to confirm you want to remove the file. (If it doesn't see me after class.) --
```
    rm: remove abc (yes/no)?
```
Respond with y. The ls command returns an error --
```
    abc: No such file or directory 
```
indicating that the file named abc no longer is there.
man unixcommand - review the manual page (help) for unixcommand, example --
```
     man sas
```
The "man page" for SAS does not contain a lot of information.
qpr -q smips file or lpr -P smips file - print file at the Smith Hall computing site (smips.
Use a different printer name to print to a different location (e.g., whlps for Willard Hall, prsps for Pearson Hall. To avoid unnecessary printing, we will not do an example.
The option, -q, on the qpr command stands for the printer queue or name. The -P flag on the lpr command also identifies the printer. A list of queued printers (usable from UNIX) is online. The list also is posted in the computing sites.

Viewing a long list of files.

If you do very much work on UNIX your list of files likely will grow to be longer than the number of lines on your terminal screen, particularly if you use the -l option to get a "long" listing. To prevent the list from scrolling across your screen so fast that you see only the bottom screen full, pipe it into a pager, such as less. The pipe symbol is the vertical bar on your keyboard (| -- upper case backslash key: ). Try this exercise: First, list some executable files on strauss without using the pipe --

     ls -lL /opt/bin

Then try piping the list into less --

     ls -lL /opt/bin | less

Use the following keys to navigate through the pager named less --

q		quit
<SPACEBAR>, d		Down one full screen
b		Back one full screen
j,		Down one line
, k		Up one line
G		Go to bottom of the file
g		Go to top of the file
/<string>		Search forward for "<string>"
?<string>		Search backward for "<string>"
n		Repeat most recent search going in the same direction
N		Repeat most recent search going in the opposite direction
h		Help (q to exit help)
-i		Toggle case sensitive. First use: ignore case differences in searches. Second use: honor case differences again.

If you use UNIX for an extended period, you likely will create several directories. One quick way to view all your files is to use the -R option on the ls command. Go to your home directory, then type the ls command, like this --

     cd
     ls -lR | less

If you are new to UNIX, you probably don't have a long list.

Use the forward slash to search forward or question mark to search backward for a file name. Use -i to toggle less to ignore case or honor case differences. Try searching for a file with contents in its name, like this

     /contents

Change your directory back to sasclass --

     cd sasclass