Most UNIX systems support the graphical user interface (GUI) provided by the X Window System. However, knowledge of UNIX is required for operations which aren't covered by a graphical program, or for when there is no X windows system available, for example, in a telnet session from a remote computer.
In our lab we use the UltraSpark and SunBlade workstations (SUN Microsystems, Inc). Please, take into account the following
IMPORTANT NOTES:
1. NEVER TURN OFF ANY OF SUN WORKSTATIONS OR MONITORS AFTER YOU FINISH YOUR UNIX SESSION. COMPUTERS AND MONITORS SHOULD STAY TURNED ON ALL THE TIME.
2. IF YOU ENCOUNTER ANY UNUSUAL PROBLEM DURING YOUR UNIX SESSION, DO NOT TRY TO FIX IT BY YOURSELF (BY REBOOTING, ETC.). ASK YOUR INSTRUCTOR OR TA FOR HELP.
As an illustration of the way that the shell and the kernel work together,
suppose a user types rm myfile (which has the effect of removing
the file myfile). The shell searches the filestore for the file
containing the program rm, and then requests the kernel, through
system calls, to execute the program rm on myfile. When the process
rm
myfile has finished running, the shell then returns the UNIX prompt
to the user, indicating that it is waiting for further commands.
The adept user can customise his/her own shell, and users can use different
shells on the same machine. Students have the csh shell by
default.
A process is an executing program identified by a unique number called PID (process identifier).
A file is a collection of data. They are created by users using text editors, running compilers, programs, etc.
Examples of files:
In the diagram above, we see that the directory ee51ab contains the
subdirectory unixstuff and a file proj.txt
Figure 2.
In order to access the system, you need to enter your login name in the text field and hit [Return]. The prompt will change and ask you for your password. Enter your password in the text field and hit [Return].
Your UNIX account is configured in such a way that the Open Windows (OW) GUI will start authomatically after you entered your loginname and password. Otherwise you would have to enter the command <ow> to start it. A typical desktop environment is shown in Figure 3.
Figure 3.
To finish your work with the OpenWindows and Solaris click right button on the mouse. A menu will appear (Figure 4). Put the pointer on EXIT and click either left of right button. A confirmation prompt will appear. Confirm your wish to exit.
Figure 4.
NOTE: If you are working from a remote computer (for example, using a telnet session), then you are not able to use the Open Windows or any other GUI. In other words you can only interact with the OS using the command line. In this case, to finish your session you have to use the command <logout>.
Example: prompt% logout [Return]
To be able to enter UNIX commands in the Open
Windows desktop you need to open a terminal window (called Command Tool
or Shell Tool). To do this click the right button on the mouse anywhere
on the free-of-icons desktop space. A pop-up menu Workspace will
appear (Figure 5). Then place the arrow on the Programs and click
the right button again. A submenu Programs will appear (Figure 5).
Figure
5.
Then move the arrow to Command Tool... (or Shell Tool...) and click the left button on the mouse. A command tool window will appear (Figure 6).
Figure 6.
This window contains a command line prompt you can use to enter your commands.
UNIX distinguishes between upper and lower cases, i.e. passwd and Passwd are not the same. The most of UNIX commands are in lower case. For example, if you type the command Passwd instead of passwd you will get an error message:
Passwd : Command not found
Detailed information about the usage of any UNIX command can be obtained from their manual pages. To access a manual page you should use the command man. For example, if you want to obtain information about the command passwd you must type :
prompt% man passwd
The information about the command will appear on the screen (Figure 7). Often such documents contain more than one page. To go to the next page press SPACE button.
Figure
7.
Example:
prompt> passwd
passwd: Changing password for yourloginname
Enter login password: (Enter your current
password) [Return]
Enter new password: (Enter your new password)
[Return]
Re-enter new password: (Enter your new password
again) [Return]
Try to remember your password and not to write
it on the computer desk or any place else. Never
tell your password to anybody!
Figure 8.
You are in alexei's home directory.
You are permitted to create new directories and regular files in your home directory. To create a directory use the command mkdir (make directory). For example if you want to create a new directory called "my_project", you type:
Figure 9.
You also can create a new directory using the Open Windows' File Manager program.
There are many different ways to create regular files such as text files, images, programs, etc. You can use the File Manager. If you work from a command prompt and you need to create a new text file, you can type cat > newfilename [Return], and then Control+D. File and directory names cannot have any spaces in them, so if you want to separate words, use periods or underlines (e.g. file.name or file_name). Do not use the following special symbols / \ & ? < > | [ ] * ;
To see a list of files in your current directory use the command ls (list). It will give you a short list. For more detailed information use the following usage: ls -l. See example in Figure 10.
Figure 10.
You see that the directory you just created is listed, too.
Now let's go through the meaning of columns of the long (detailed) listing output.
drwxr-xr-x 1 alexei staff
732 Oct 30 1997 mkinstalldirs
-rw-r--r-- 1 alexei staff
10483 Oct 30 1997
props.c
-rw-r--r-- 1 alexei staff
179 Oct 30 1997 props.h
-rw-r--r-- 1 alexei staff
10572 Aug 27 18:59 props.o
(permissions) (owner) (group)
(size) (date and time (filename)
of last change)
The letter d in the first line
means directory
The first column show file permissions. The three basic operations on
a file are "read", "write" and "execute". The permissions required to perform
these operations are denoted by "r","w", "x". The "x" permission is needed
for compiled programs and for any shell script (command file) that you
intend to use directly as a executable command. For example, the file cls
(in the previous figure) is executable and can be run by alexei only.
The "r","w" and "x" permissions can be specified independently for
the owner of a file ("u") , for users in the owner's group ("g"), and for
all other ("o"). To change permission use the command chmod. Note,
you can only change permissions for the files created by you.
Example:
prompt% chmod u+x filename [Return]
You made the file filename executable (x) for owner (u). Group
and others are denoted by "g" and "o", respectively.
To travel around the file system use the command cd (change directory). Its usage is:
prompt% cd <path to folder where you want to go>.
For example, to go into the new directory called my_project, type cd my_project (Figure 11).
Figure 11.
The command ls was used to check the content of the directory.
It is empty because we did not create any file inside this directory.
Other commands for operating with files are:
cp - to copy files,
mv - to move files,
rm - to delete files.
cat or more - to direct a file content on the screen.
Detailed information about these commands can be obtained from the UNIX
books in Room 203, from the manual pages, and from the links provided in
EES254 webpage (http://www.earth.rochester.edu/ees254/lab1.html).
prompt% textedit <name_of_the_file>.
Alternatively you can use the Programs menu, the same way as we discussed before to start the Command Tool.
Executable command files (scripts) can be also edited by textedit tool.
Example:
prompt% imageview image.ps & [Return]
(To learn why the ampersand symbol is used at the end see the section
"More About Commands" below.
All the workstations are connected to a laser postscript printer.
To print your text or image file use the command lp <yourfilename>.
Example:
prompt% lp image.ps
Many files can also be printed directly from application programs such
as textedit, pageview, or imagetool.
1. If you start a command or a program from the command line, you
cannot use the command line again until the previous command (program)
is finished. To be able to work with the command line while your program
is running, you need to use a background mode. To do this add the symbol
& after the command name.
Example:
prompt% textedit & [Return] (text editor window will appear)
prompt% (ready to accept new command)
2. You can redirect the output of any command to a specified file instead of a terminal window by using > symbol. The format of a command line that redirects output follows:
command [arguments] > filename
Example:
prompt% cat progr.f > myfile (the content of the file "progr.f" will be directed into the file "myfile")
Using >> instead of > will append the output to the end of the file instead of replacing its content.
NOTE: This method is used in GMT-scripts to create postscript images. So it is very important to understand the difference between > and >> to be able to successfully work with GMT-scripts.
Standart output of a command (a program) can be directed into the input of another program by using symbol | (pipe). This feature of UNIX is also often used in GMT-scripts.
Example:
prompt% cat progr.f | lp
[the content of "progr.f" (output of the cat command) will
serve as the input of the lp command. As a result the "progr.f"
content will be printed]
As far as you have a UNIX account (login name) in our computer system
you can receive and send electronic mail. Your e-mail address is:
yourloginname@earth.rochester.edu
To read and to send e-mail you can use the Mailtool programof the OpenWindows or the commands mail or mailx. Also a very popular mail program is pine, which can be started for the command line.
You can work with UNIX from a remote computer. It is important to realize
that in this case you cannot use the advantages of the GUI and will have
to use the command line.