Computer LabsUNIX FAQ This document is provided to answer questions about the UNIX system that new users frequently have. Among other things, some of the major services and resources available on the internet by using UNIX are:
First, ask yourself some questions: • Am I sure that I typed the password correctly? Remember, UNIX is case sensitive. So if the password says that it's lower-case, type it that way. If you entered the password incorrectly 3 times in a row, you will be unable to log in to that host for a few minutes. • Am I enrolled at UTD? If you were not registered at UTD for one semester, your account will have been deactivated and you must speak to the CAs to have it reactivated. If you want to log into departmental machines, you must acquire an account from that department. • Will logging in a different way help? Occasionally you may type your login ID and password correctly, but the UNIX systems won't accept it. Try something else. For example, if you are trying to login to a UNIX host on Sunray or UNIX terminals in the Jonsson Lab, but it doesn't work, try to use SSH from Windows. Or if apache won't accept your password, will infoserv? • Have I exceeded my disk usage limits? This can also prevent you from logging in. Please refer to the section, How much disk space do I have? below for more information. If you have exhausted all ideas, the CAs or the Help Desk will be able to look up your password if you have not changed it, or assign you a new password which should become active within 24 hours. Always remember to write down the exact error message to show them when you need help, and bring your student ID. This way, they will be able to help you more quickly and precisely. In order to change your password, you will need to visit the NetID site at netid.utdallas.edu. If you are unable to change your password on this site for any reason, contact the Help Desk or the Lab CAs so that they may "reset" your password. You will then be able to create a new one on the NetID site. When I log in, the computer logs me right back out. What do I do? If you have exceeded your disk quota and try to log into a Sun Solaris (Sunray) or Linux station, you will be logged in, and quickly logged back out. This means that you must first log in using a Windows machine, access the SSH command line interface, and then delete files until you are under your disk usage quota. (See the section entitled, How much disk space do I have?) To obtain complete online information on UNIX commands, use the man command to display manual pages. Type man followed by the command you need help on. For example, if you need help on the compiler gcc, enter: man gcc If you are not sure of the command, you may enter the man -k subject command, where subject is replaced by the topic you want to search for help on. It will list the headings of commands that are related to the subject. For example, to view a list of commands related to the topic 'directory:'
You could then use man to get more information about whichever command seems most relevant. How do I change my login shell? You can change the UNIX shell that is started when you log in with the nispasswd command:
Now type the path and name of the shell you want to use. Examples are: /bin/bash, /bin/tcsh, /bin/ksh, /bin/sh, /bin/csh. Please allow one hour for the change to take effect. Because exceeding your allotted disk space can make you unable to log in, you want to make sure that your disk usage remains below your limit, or quota. To see what your quota is, type vxquota -v at the UNIX prompt. The output will be of the form:
This shows you which directory contains your home directory, how many 100 kilobytes you are using, how many you are allotted( ie: your "quota"), and what the absolute limit is. You may use the command du to see a listing of your disk usage by directory. Keeping your disk usage below your quota will ensure that you avoid any penalties for excessive disk-space usage. You may remove unwanted files by typing: Disk space will be increased only when university-related needs require it. To find out if you qualify, contact the Help Desk. The most common email program from UNIX is pine. Just type pine from the prompt. Once pine is started, all the menu options for everything you want to do with email will be on the screen. Just press the key for the action that you want to do. If you want to configure pine to have a different default printer, for example, press "s" at the Main Menu, and then "p", just as it instructs you to at the bottom of the screen, and then just follow the other menus and instructions. To save a message to a file while you are viewing that message, press "e". To save an attachment to disk, press "s" while you are "viewing" that attachment. If you wish to Compose a message, press "c" from any of the major screens. The email address you enter should be of the format:
Note that you have several different mail folders, for example, "INBOX", "received mail", etc. Disk space is limited, so be sure to delete any old messages from the "received" mailbox, as well as your "INBOX." To run Netscape from a Jonsson lab Sunray, type netscape from a terminal window. TCS does not currently support home use of web browsers. You can copy files from one directory to another using the cp command or move them using mv. mv may also be used to "rename" files. To transfer files from one UNIX host to another, or to/from your home PC, use ftp. Users can also use their home directory (drive H:) in Windows. "Dot files" are the hidden system files which are in each user's home directory. If yours are outdated or have been changed for the worse, you may wish to copy the master dot files over your own. The most recent dot files are kept in a directory from which all the users can copy. To copy the files, make sure you are in your home directory, then type: NOTE: This will overwrite your existing dot files and put old dot files in .olddots. So any changes you make to your dot files will be in .oldots. Files that were in your directory for some amount of time may be recovered after accidental deletion using the recover command. A file deleted from you home directory can be restored at any time within a one-month period since deletion. A procedure to recover a file would be as follows: if today's date is 2/19/04 and the file birthday.txt was accidentally removed on 2/18/04:
This may take a while, especially if you are recovering a file from long ago. In the above example you would, of course, enter your own path and filenames instead of jsmith's, and use the date from the last full day that the file existed. (As backups are done overnight, the file must have existed for at least one night to be recoverable.) To compress archive files and directories, you may use the following commands: compress, zip, gzip, tar (tar is an archiving utility, not a compression utility). To un compress files, use the commands un compress, unzip, gunzip, tar -xf, followed by the filename, for files with the extension .Z, .zip, .gz, .tar, respectively. For specific information on each command, view the man page for each. where filename is the name of the file that the output will be saved to-- not the name of the file you want to test. This will place you in a shell. Type any commands whose output you want to record. To end the script, type exit. This will exit the shell that was started and end the script file. Remember, if you do not exit the scripting shell, the output will not be saved, and you will remain in the subshell. There is now only one printer available in Jonsson lab.
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