handout This focuses on UNIX survival skills. The intent is to introduce you to a select set of UNIX commands and background knowledge of UNIX so you can survive EE 2381. SEAS has a number of UNIX public compute servers, including DEC alpha, DEC Mips, Sun Sparc and more recent SGI architectures. There are also a number of PC's based labs. All UNIX files are stored an a central file server. This allows one to logon to any computer server and have complete access to all of your files. One can also access these files from a SEAS networked PC, but it may require some setup to do this. There are a number of public terminals and printers through out SEAS. Public terminal areas include 316 Caruth Hall, the open area in the SIC building and the Patterson labs. You can use any public terminal and you are allowed to print on any printers located in public areas, provided that you are within your paper quota. Generally speaking, there is at least one printer in each of the public areas. You can also access the computer servers from the dorms. Verilog only runs on the Sun Sparc machines "nova" and "pulsar". In the lab, you will need to logon to a PC and then access one of these machines. Since you will need a gui (graphical window), you will need to start the program called "exceed" from the start button on the PC. Once "exceed" is started, say yes to using jobber and this should bring up a "chooser" which lists a number of different machines that you can access. Chose either "nova" or "pulsar". To begin with, you have been assigned a SEAS UNIX account. While you may have accounts on other SMU UNIX machines, you will need to use your SEAS UNIX account to logon to a PC in the lab. To login, you will need to provide your account name and then provide the correct password. If you have forgotten your account name, I can look it up for you. If you have forgotten your password, you will need to contact a SEAS computer operations manager and have them reset your password for you. It is a good a idea to change the password on your account on a regular basis. When selecting your password, it helps to use both upper and lower case letters, some digits and other printable characters. Some control codes can be used, but you do need to be careful as some telnet connections "eat" select control codes. To change your password, use the command yppasswd at the UNIX prompt. To get details on how to use yppasswd, use the command man yppasswd Note that it may take several seconds before it is displayed. Also note that there is a related command called passwd that can only change a local password (which you do not have).
UNIX has a substantial amount of documentation on-line, you just need to know how to access it and where to look. On-line help is called the "man pages" because historically, they could be printed to form a manual. The general form for accessing a man page for the command command_name is man command_name How do you figure out the name of a command? By using either the command man -k query or apropos query all of the header information for each man pages will be searched for the word "query" and displayed. So if you wish to see what editors have man pages, type the command man editor and you will get 31 listings. Note that some may be duplicate listings. If you are interested in learning more about man, type the command man man and you will probably see more than you ever wanted to know about man. When you login to your UNIX account, you are placed into you "home" directory. From your home directory, you may have several sub-directories which in turn may have sub-directories. To change to a subdirectory named files located in your home directory, use the Change Directory command as cd files Note that you can always return to your home directory using the Change Directory command invoked as cd To see the name of the directory in which you are currently located, use the Print Working Directory command pwd In UNIX, the current working directory (the one you are currently in) is referred to as "." while the parent of the "." directory is "..". So if you wish to return to the parent directory of file in the example above, you can use the command cd .. which would return you to your home directory. Directories contain files and directories (and a few other exotic entries such as sockets, symbolic links and FIFOs). To list the contents in a directory, use the LiSt command ls Since this is one of the most frequently used UNIX commands, it would be a good idea to read the man pages on ls to see what options it has. In general options are activated via flags
appended to the command. For example, one of my favorite options is -F which tells ls to indicated the type of directory entry by adding a special character at the end of the file name. To use this command, type ls -F I like it as it helps me to quickly distinguish files from directories and shows which files are executable. To remove a file named old_file, use the ReMove command as rm old_file To MoVe a file named old_file into a sub-directory named folder which is contained in the current directory, use mv old_file folder Note that if there was no sub-directory folder, named this would have the effect of renaming old_file as folder. A safer way to move the file old_file is to invoke the command as mv old_file folder/ The "/" at the end of folder makes sure that you intend the file old_file to be moved to the directory folder. To make a directory named new_folder in your current working directory, use the MaKe DIRectory command as mkdir new_folder To remove this directory use either the ReMove DIRectory command as rmdir new_folder or use the rm command as rm -r new_folder Note that there is a difference between the two commands. The rmdir command assumes that the directory to be deleted is empty while the rm command will remove the directory new_folder as well as all of its contents. Unix has the ability to redirect input and output of programs, just as DOS does. Suppose that prog is a program whose output appears on the screen (called stdout). Then the command prog > data will redirect the output of prog from the stdout into the file named data in the current working directory, provided that the file data does not exist (and technically your noclobber flag is set for your shell). Now suppose that prog also takes input from the keyboard (called stdin). You can redirect the input to a file named commands via prog < commands To do both simultaneously, use prog < commands > data Next, suppose that you want the output of the program named prog to be modified by another program named prog-jr. Assuming that prog-jr has its inputs coming from the stdin and its output
going to stdout. Then you can "pipe" the output of prog into prog-jr as prog | prog-jr Note that "|" denote a pipe whose input is stdin and whose output is stdout. What the pipe does is connect the stdout of one process to the stdin of another process. Finally, suppose you want the input of prog to be the file commands and you want the overall output to be sent to the file data. This can be accomplished several ways: prog < commands | prog-jr > data cat commands | prog | prog-jr > data cat commands | prog | prog-jr | tee data Here the command cat says to direct the contents of the file commands to the stdout while tee makes two copies of its input one goes to the screen while the other goes to a file named data. Unix is a multi-tasking, multi-user OS. Hence you can (and do) have several process running at simultaneously. A process or job is in the foreground when it controls access to the terminal screen and keyboard. A foreground job can be suspended with a "^Z" command. This immediately stops a job, but it may have queued up output for the terminal which will continue to print until gone. You can now go on to another task if you wish with this job suspended. Execution of the job can be resumed by issuing a ForeGround command as fg Alternatively, you may continue to execute the job in the background by issuing a BackGround command bg At any point in time, you can bring a background job to the foreground, but you first need to identify this job. This is accomplished using the command jobs which will list all of your current jobs. Identify which one you wish to resume execution,...