Computer LabsIntroduction to UNIXThis tutorial contains step-by-step instructions for using the UNIX Operating System on University of Texas at Dallas (UTD) UNIX Servers, such as apache and infoserv. This document assumes basic computer knowledge. Throughout this document, the terms “host” and “server” will be used interchangeably, because they both mean essentially the machine that you connect to and execute or manipulate files on. The University servers are designed to be very structured and well supported UNIX systems. This is a lengthy document. To facilitate ease of movement, the following links are provided to each major section: In addition, each major section includes a top link, which returns the reader to this table of contents. Because each of the servers has a different purpose, different applications are available on each server. Some of the major servers and the applications/languages available on each include:
For a complete command list, see UNIX Commands . Logging In, Changing Your Password, and Logging OutYou may access a UNIX server from a PC through the UTDNet menu on or off campus by: • selecting the menu option for the desired server, such as “ APACHE (Applications Server) ” • telnet to the server from another UNIX host by typing, for example, telnet apache when you are already logged into another machine, such as inca. Remember that although you are logging in to apache you remain logged in to inca; therefore, to completely log out, first log out of apache and then inca (in this example). • by entering (for example) apache from a WYSE terminal, or by directly entering your username and password on a SUN work station or NCD Terminal at the machine login prompt. For more information on dialing in from off-campus, see TCS's Communicating with the UTD Computer System from Off Campus. For more information on connecting to UNIX Servers on-campus, see Using the Campus Ethernet and the UTDNet Menu Software. You must have a user account, including a user (or login) name and password, set up on the UNIX platform before you can login. To get a faculty sponsored UNIX account, fill out the Academic Computer Account Request Form and request UNIX on it. For an On-demand instructional UNIX account, or to obtain an Account Request Form, see the computer assistants (CAs) in the Jonsson Computing Center (UNIX lab) or McDermott Microcomputer Center. Please allow at least 24 hours from the time you have turned in the account request form until the account becomes active. UNIX is case sensitive; that is, it knows the difference between upper and lower case letters. (Most commands and system directories are in lower case. User names are also in lower case; therefore, you should not login with upper case letters. Be sure to enter your username and initial password exactly as it is printed by the Account Management System, on the sheet you received for the UNIX platform. Also remember that you are held accountable for any activities done under your account, and it is therefore quite important to keep your password private. Logging In You will now be prompted for your password as shown: You will want to change your password to one that you will remember, but that another person would not be able to guess. You change your password with the nispasswd command. Changing your password here will only change your password on the UNIX platform . First, type in the command: You will be prompted to enter your old password once and your new password twice as follows: Password must contain at least two alphabetic characters and at least one numeric or special character. Should you forget your password, see the computer assistant (CA) in the Jonsson Computing Center to get a new one. Please allow 24 hours for your account to become active. To leave UNIX when you are logged in to a WYSE terminal or from Dialup, enter the log out command: If you are running X-Windows, such as from an NCD term in Jonsson lab, you must depress the “setup” button on the upper-right corner of your keyboard. Click on the “Login” menu in the “Console Window” that appears and select the “Log out” option. Re-affirm the log out when prompted, and wait until the “Login Chooser” menu is displayed. Remember, simply closing all your xterm windows may not log you out. Executing UNIX CommandsHelp on UNIX
You could then use man to get more information about whichever command seems most relevant. The number in parentheses is the manual section. The UNIX manuals are divided into 9 major sections:
In many cases, the same topic will be in multiple sections (e.g. mkdir in the above example). By default, the man command displays the first section it finds the topic in. To override this, you can type man -s# topic for a particular section. {apache:~} man -s2 mkdir man calls a command known as more to display the manual page. Use the following keys to control the scrolling capabilities while using more:
You will often need to use certain keyboard keys such as the Back Space key. Depending upon the terminal type you are using, the key actually labeled Back Space may not work. First, try the Delete key, then Back Space, and finally Control-H (or Ctrl-H).
Note: If you find your terminal “frozen” pressing Control-Q can unlock it. Directory and File CommandsListing Available Files Use the ls command to list the files in a directory. For example:
Use the -a option to list all files (includes your dot files such as .bash_profile, which you usually won’t care to see):
Use the -l option to display a long listing of files and directories, which includes permissions, hard link count, file ownership, file size in bytes, modification date and time, and file or directory name:
You may put all the options, or “switches,” together for a complete listing of all files. Because this list will scroll faster than is readable, you may pipe (“|”) it through the more command, as such:
Note: This command has actually already been programmed into your environment as the shortcut, or “alias,” dir. This means that anytime that you type dir, the command ls -la|more will be executed instead. To see which other aliases we’ve provided you with, type alias at the command line. For information on how to make your own aliases, which you can insert into your own .bashrc or .cshrc file to have them load automatically each time you log in, view the man page on alias. Directory Commands To display the name of your current directory, use the pwd command (print working directory). For example: You may also have noticed that your prompt tells you which server you are logged into. To the right of the host name, your current directory is also displayed. In the example above the user is in his home directory, which is denoted by the tilde ~, or ~jsmith. To change your current directory to a new directory, use the cd directory_name (change directory) command. If you do not specify the directory name, you will be placed in your home directory. cd .. will take you up one level in the directory structure. To create a new directory, you may use the mkdir command (make directory). You can then use the ls command to see that the new directory is there. To remove a directory, you must first make sure that you delete all the files in that directory, including “dot files” and then use the rmdir command (remove directory) For example: To find out how much disk space you are allotted, use the quota command:
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. File Commands The more command will display files to your screen. More information about using it can be found in the man command section above. The cp command (like MS-DOS COPY) copies a file. You first specify the name of the file you want to copy and then the name of the file to be the copy. The following cp command copies the contents of the file payroll.tst to a file called payroll.old. The rm command (like MS-DOS DEL) removes files. The chmod command allows you to change access rights, “permissions,” for the user (i.e.: you), members of your group (i.e.: other CS students), and all other users to access your files and directories. You control their permissions to read, write, and execute. The syntax is then : chmod ugo+/-rwx filename where you may use any combination of u, g, or o, either + or -, and any combination of r, w, or x, to respectively add or subtract the indicated permissions from the users that you specified. For example, if you create a public_html directory to have your own web page, you will need to give other users access to read from that directory and change to that directory, but you will probably want to disallow others from writing to that directory:
From this line of the directory listing you can see first that this is a directory, second that the read, write and execute permissions are enabled for the user, and third that group users then other users each have read and execute permissions, but no write permission. Generally you want to disallow other users to write to your files. Printer CommandsPrinting is done by the lp command. The general syntax is lp -d printer_name filename. The only available printer is ljacc (for the laser printer in the Jonsson UNIX Lab). For example: Note: The line printer can only print pure text files-- Not postscript or graphics. For great preprogrammed printing options, such as double-sided printing, look at any of the options listed on the first page of a print-out. You may also use the genscript filename command for fancy printing. To print on your locally-attached PC printer, use the special UTD-developed command: printpc filename and then, as instructed on the screen, press Alt-W. To see the status of your print jobs, use The UNIX servers have three editors available. They are:
Electronic Mail can be sent by either the Pine or Elm programs. Pine is the recommended package and can be invoked by typing pine. It is very simple to use, but if you need more information, see the TCS's Electronic Mail on the UNIX System. Elm is for more advanced users and can be run by typing elm. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||