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CONTENTS

• Introduction
• Things to Remember
• Getting Started
  • Connecting to a Unix Computer
  • Logging In and Changing Your Password
  • Terminating a Command, Halting Screen Output and Logging Out
• Files
  • The File System
  • Unix Command Syntax
  • Table of File Commands
  • The ls Command
  • Setting File Permissions with chmod
  • Some Special Characters
• Input/Output and Redirection
• Tailoring Unix
  • Special Files
  • Shell Variables
  • Sample .profile and .variables.ksh Files
  • Sample .kshrc File
• How to use Command History
• Job Control
  • Background Jobs
  • Terminating Runaway Processes
• How to Get Help
• Appendix A: Printing Commands
• Appendix B: Some Utility Commands
• Appendix C: Setting File Permissions with Access Control Lists

INTRODUCTION

This document is intended to help the new user of the computers that run a version of the Unix operating system. At UVa, Information Technology and Communication (ITC) has IBM RS/6000 servers (RS) that run a version of Unix called AIX, Sun workstations and servers that run SunOS or Solaris, and Silicon Graphics workstations that run IRIX.

The RS/6000 computers at UVa have ITC's Unix Menu System (Umenu) installed as the default configuration. (See document U-001A, "Using UVA's Unix Menu System" for more information on Umenu). If you prefer to work from the Unix prompt, you should disable the Umenu system by selecting "System Customization" from the main menu. The next time you log in, you will get the Unix prompt, from which the commands in this document can be issued. You can use the Umenu system at any time by typing umenu at the Unix prompt.

The command interpreter described in this document is the Korn shell, which acts as an interface between the user and the Unix system. The Korn shell is the default shell on ITC's Unix systems, so user commands are generally the same on each Unix machine. Any differences in a command among the machines will be noted in this document.

In order to include the information that a wide audience of users might want to know, this document has been packed full of information. There is probably more here than you will want to try to assimilate in one sitting. Try reading a section at a time and experimenting on your account as you work your way through the document. There may be some sections for which you currently have no use; skip them. They will still be there when you need them.

Things to Remember

1. The Unix operating system is case-sensitive; i.e., a command in lower-case letters is interpreted differently from one in capital letters. ALWAYS turn off the Caps Lock key on your terminal or microcomputer before you log in. Enter all commands in lower-case letters unless otherwise instructed.
2. Be sure to end everything that you type with a carriage return (marked Return). The Return key is shown as <CR> in this document. The computer doesn't know you are trying to tell it to do something until it sees a carriage return, so if the computer seems to be ignoring you, check to see if you forgot to press the carriage return.

GETTING STARTED

Connecting to a Unix Computer

(NOTE: If you will be using the X Window System, refer to document U-014 for login instructions.)

1. If you are accessing a Unix machine from a system running MS-Windows (95/98 or NT):
   1. Select Start, then Run and issue the command telnet hostname, where hostname is the is the name of the host you want to connect to (typically blue.unix) and click OK. (If you have a telnet application other than the standard windows telnet you'll need to follow the instructions provided by the vendor for reaching a host.)
   Skip to the next section entitled "Logging In and Changing Your Password."

2. If you are using a Macintosh that is connected to the UVa network and running the Macintosh Finder, follow the steps below.
   1. Turn the computer on.
   2. Find the icon or picture labeled NCSA Telnet (or just Telnet). (You may or may not have to log in to an AppleTalk server to find it.)
   3. Double click on that icon.
   4. Choose "Open connection" from the ``File'' pulldown menu.
   5. Type the name of the computer on which you have an account in the box labeled "Host/Session Name."
   6. Click on the button labeled "Connect."'

   Skip to the next section entitled "Logging In and Changing Your Password."

3. If you are dialing in to UVa, follow the instructions found on the
   ITCWeb "Dial-In Access" page.

   Skip to the next section entitled "Logging In and Changing Your Password."

4. If you are logging in at the console of a workstation, the login message and prompt will already be on the screen. If not, press the Return key to refresh the screen. Continue with the login process outlined in the next section.

Logging In and Changing Your Password

You should now be looking at the computer's login prompt.

1. In lower case (Unix is case-sensitive), type the login ID that was given to you; it will probably be your initials with an alphanumeric suffix.

2. After you have typed your login ID, press the Return key.
   The system will respond with

                  Password:

   Enter the password you were given, followed by a carriage return.

3. Once your password has been accepted, you will be asked to change it. Enter a new password with six to eight characters including at least one numeric or special character. The system will let you know if the password does not meet our security requirements. You will be asked to enter the password twice for typing verification. Once this process is complete, you will see a welcoming message.

   Choosing a password that provides system security is important, not only to protect your files, but also to protect the entire system from being accessed by the mischievous or unscrupulous. Do not use your name or initials or any word that can be found in the dictionary. Putting a number in the place of a letter (the digit 1 for the letter l, for instance) is also not secure, nor is putting a digit at the beginning or end of a word or name. It is safer to use a sequence that is meaningful only to you or to use two words, omitting vowels and joined with a character such as a hyphen or comma.

   After changing your password, some users will see the message:

                  Enter terminal type [default is vt100]:

   The University's microcomputer facilities and many communications packages support vt100 terminal emulation. If you are not using one of UVa's computers, you may want to check your documentation to see what emulation is being used. However, in most cases, vt100 should work fine. Press the Return key to accept vt100 unless you are using some other terminal type (e.g. vt102, vt220, sun, adm5, tek4107, xterm), in which case you should type in the appropriate terminal type.

   Finally you will see the system's prompt. The prompt varies from machine to machine, but may include a $, which is the Korn shell's default prompt. New RS/6000 users will be presented with UVa's Umenu system. You will want to choose "Go to Unix" from the main menu in order to get a Unix prompt. (To disable Umenu, choose "System Customization" from the main menu.)

   The machine will now wait for you to enter a command.

4. You can change your password at any time by typing:

                  passwd<CR>

   at a Unix prompt. The system will prompt you for your old password, then for your new password. Choose a password following the guidelines given in Step 3 above. You will be asked to enter it twice for typing verification.

Terminating a Command, Halting Screen Output and Logging Out

1. Break Sequences to Terminate a Command

   If you want to stop a command before it completes execution, press the key sequence from the table below which is appropriate for the type of terminal you are using. This should return you to your initial prompt.

   Break Sequences
   Terminal	Key(s)/Menu Sequence
   Host Explorer on Windows 95/98 or NT	Ctrl-c
   Telnet on Windows 95/98 or NT	Ctrl-c
   NCSA Mac Telnet on Macintosh	Ctrl-c or Network->Send "Interrupt process"
   RS/6000, Sun or SGI console	Ctrl-c

2. Halting Screen Output

   If you want to temporarily halt output to your screen without terminating the execution of the command, enter Ctrl-s. Start output again by entering Ctrl-q. If you are on a microcomputer running

3. Logging Out

   When you are ready to log out, type exit or press Ctrl-d.

FILES

The File System

Unix uses a hierarchical (or tree-structured) directory system to store files. A diagram of a portion of a file tree is shown below, with the directory /, called the "root" directory, at the top of the tree.

In the Unix system, all the commands you type, as well as peripheral devices such as disk and tape drives, can be specified as a path to a file. A path name can be absolute, meaning it begins with /, or relative to the directory where you are attached, called the current or working directory. Directory names are separated by additional slashes (e.g., /etc/passwd). In the figure above, some of the directories shown are:

You will be assigned a directory with your login ID as its name when you are given an account. The user accounts reside in the /home directory. When you complete the login process, you will be attached at the directory /home/your-login-id in the file tree. Your login directory is called your HOME directory where HOME is one of the Unix system's shell variables. Shell variables are read by many Unix commands and can be given values either by the system or the user. For more information about shell variables, see "Tailoring Unix" below.

You can create other directories and files below your HOME directory as you need them. For instance, if your login ID is "abc3f," you may be assigned a HOME directory with the name /home/abc3f. If you create a directory named "docs", you could put all the chapters of your thesis in that directory. Then the full path of a file named "chap1.thesis" would be

               /home/abc3f/docs/chap1.thesis

Unix Command Syntax

The typical syntax of a Unix command is

               command arguments files

where the command options, also called arguments, are usually preceded by a hyphen (-). More than one file name may generally be given. Optional arguments will be surrounded by square brackets ([ ]) in the documentation on each command.

The table on the next page gives some commands and selected options that are useful for manipulating files and moving around in the file system, including how to list the contents of a directory (ls), the contents of a file (cat) and how to move from directory to directory (cd). To get complete information on each command and all its options, use man command to view the on-line documentation. The syntax is:

               man command

 

Table of File Commands
Command	Meaning	Result
cat filename(s)	catenate	list contents of filename(s) to the screen, one after the other
cd directory	change directory	change working directory to directory; if directory is omitted, changes to your HOME directory
cp file1 file2	copy	make a new copy of file1 called file2
diff file1 file2	difference	list the differences between file1 and file2
find dir -name file -print	find	find files beginning search at directory dir matching file and print the entire pathname
grep [-i] string file(s)	global regular expression processor	search file(s) for string and list path and line if found; use -i option to ignore case of string
head filename(s)		list first ten lines of filename(s)
ls [-AlpsCF]	list	return a list of the files in the current directory (see example below) -A all entries, including files beginning with period (.) -l long format -p put slash (/) after directories -s give size in kilobytes (or blocks, SGI     and Solaris) -C multi-column listing (with short     format) -F put slash (/) after directories, asterisk (*) after executables
mkdir dir	make directory	create a new directory named dir
more filename(s)		list contents of filename(s) a screenful at a time; scroll forward with the space bar, back with b, end with q or Ctrl-c.
mv name1 name2	move	rename file name1 to become name2 or move a file name1 to directory name2
page filename(s)		same as more
pwd	print working directory	list the pathname of the working (current) directory
rm [-i]	remove	delete a file; the -i option queries for y or n response; default n (do not delete)
rmdir directory	remove directory	delete directory; directory must be empty
tail filename(s)		list last ten lines of filename(s)
tee filename(s)		input to tee is sent to both filename and standard output
wc filename(s)	word count	list the number of lines, words and characters in filename(s)

The ls Command

Sample output from the command ls -Al is shown below (use ls -Alg on Solaris), with column numbers at the top for reference with the explanation following.

       1        2      3      4     5         6        7            8
   _________________________________________________________________________

   -rm-r--r--   1    abc3f   usr   4193     Jun 10   10:11    .history
   -rw-r--r--   1    abc3f   usr    626     Jun  6   12:08    .kshrc
   -rw-r--r--   1    abc3f   usr    338     Mar 17   16:43    .mailrc
   -rw-r--r--   1    abc3f   usr   9156     Nov  9   13:06    .newsrc
   -rw-r--r--   1    abc3f   usr    800     Jun  6   14:28    .profile
   -rw-r--r--   1    abc3f   usr   1424     Jun  6   14:28    .variables.ksh
   drwxr-xr-x   2    abc3f   usr    144     Jun  9   16:21    News
   drwxr-xr-x   4    abc3f   usr    144     Apr 16   14:34    docs
   drwxr-xr-x   2    abc3f   usr     64     Jun  3   10:34    fortran_progs
   -rw-r--r--   1    abc3f   usr   3289     Nov  9   10:09    junk

Column 1:	Ten characters giving file information; first character (-, l or d) is type of file; remaining nine are permissions. The first entry will generally be one of the following: d = directory l = symbolic link to a file - = ordinary file The next nine characters specify the file permissions given to user abc3f (first three characters), the group to which abc3f belongs (next three), and the other users on the system (last three). At UVa, the group to which the user belongs will generally be the same as all other users. On the RS/6000s and Sun/Solaris, it is possible to give a selected group of users permissions to a file; see Appendix C, "Setting File Permissions with Access Control Lists." The permission characters are as follows: r for read w for write x for execute - for permission denied If all permissions are given for a file, these entries would be rwxrwxrwx which gives the user, group and other read, write and execute permissions. For more information, see the section "Setting File Permissions with chmod."
Column 2:	links; for a file, this is the number of links to the file (see the man page on ln to read more about links); for a directory, it is the number of directories it is in (its parent and itself) plus the directories under it.
Column 3:	owner of file.
Column 4:	group to which owner belongs.
Column 5:	number of bytes (characters) in the file.
Column 6:	date file was last modified.
Column 7:	time file was last modified.
Column 8:	file name.

Setting File Permissions with chmod

One way to set the permissions on files and directories is with the chmod command. The command syntax is as follows:

               chmod mode filename

where

               mode         is a string of users and permissions.
               filename   is the name of the file whose permissions are to be changed.

The example shown below gives mode as a string defined to be who_permission where who is

           u = user          (abc3f in the example above)
           g = group         (usr in the example above)
           o = other
           a = all (default)

and

           + = gives permission
           - = denies permission

and permission is

           r = read
           w = write
           x = execute

Example 1:	You want to remove read permission on a file named "personal" from everyone except you. Use the command:                chmod go-r personal
Example 2:	You want to make a command file called "printit" readable and executable by everyone. Use the command:                chmod ugo+rx printit     or     chmod a+rx printit

On the RS/6000s and Suns, you can give permissions to a selected group of users. See Appendix C, "Setting File Permissions with Access Control Lists."

Some Special Characters

Some characters have special meaning to the Unix system's Korn shell interpreter. These can be used so that you do not need to type long names of directories and files, or they can be used to "wildcard" (match more than one) directory and file name. Some of these characters are defined below.

INPUT/OUTPUT AND REDIRECTION

One of the features provided by the Unix operating system is the ability to redirect output from a command to a file or to another command. Some of the characters used for redirection by the Korn shell are:

Combining redirection characters with the files called standard input (the keyboard, file descriptor 0) and standard output (the screen, file descriptor 1), standard error (file descriptor 2), and the command tee, you will have the tools and symbols you need to make use of redirection. Study the examples below to get some ideas.

1. To use electronic mail to send a letter you have prepared with an editor and saved as a file called "welcome.letter" to xyz3g@virginia.edu:

                  mail xyz3g@virginia.edu <welcome.letter

2. To send all the FORTRAN compiler error messages to a file called "errors" rather than have them come to the screen:

                  xlf myprog.f 2>errors

3. To send the output from the ls command to the file "ls.output" rather than to the screen:

                  ls >ls.output

4. To join "file1" and "file2", send the output to the sort command and then put the sorted output into a file called "sorted.big.file":

                  cat file1 file2 | sort >sorted.big.file

5. To sort another file and append the output to "sorted.big.file":

                  sort file3 >>sorted.big.file

6. To send output from the sort command both to a file "new.file" and to the screen:

                  sort filename | tee new.file

TAILORING UNIX

Special Files

It is possible to customize your Unix environment by editing the appropriate files. You can change the names of commands as well as specify which command options are selected. Some commands, like mail and trn (a USENET news reader), check for a specific file, often called a reconfiguration file (notice the letters "rc" at the end of many filenames) from which they get initialization information.

The following are some of the reconfiguration files you may see when you issue the ls -A command.

Default .profile, .mailrc, .joverc, .variables.ksh and .kshrc files exist, but you can create your own versions of these files to set your initialization preferences. The .history file is created automatically by the Korn shell and the .newsrc file is created by the trn program. You can look at and modify any of these files except the .history file, which is not a text file. More information follows on the .profile, .variables.ksh, .kshrc and .history files, but first it will be useful to know more about Unix shell variables.

Shell Variables

The Korn shell sets up some variables called shell variables which are read by Unix commands. One way that the Unix environment can be tailored is to change the values of these variables. A complete list of the shell variables set up by the Korn shell can be found on the ksh man page.

A shell variable (also called an environment variable) is usually written in upper-case letters (remember that Unix is case-sensitive) and its value is often a pathname to a directory or file. Many Unix commands read the value of one or more Unix shell variables when they execute. For example, full screen editors like JOVE or Vi need to know the type of display you are using, so they read the value of the TERM shell variable to get the information needed for full-screen display.

Some shell variables are described below.

The PATH shell variable has special importance since it names the directories (separated by colons) that the system will search in for commands you type. The directories are searched in order from left to right. For example, if you invoke the ls command by typing the complete path /bin/ls, the value of PATH would not be used since there is a / in the command. However, if you type ls, the system searches the directories given in the PATH variable. The first executable file named "ls" found in one of the PATH directories will be executed. If no file is found, the error message ksh: ls: not found will appear.

To see the current value of the PATH, issue the command:

               echo $PATH

The directory specified by "." represents the current directory.

If you create your own executable command files (e.g., C programs or Unix shell scripts), you could put them in a "bin" directory in your HOME directory. To get the system to search that directory, set your PATH value to

               PATH=${HOME}/bin:${PATH}

which will cause the system to search your bin directory before searching other directories.

To see the current values of shell variables, issue the command set.

Sample .profile and .variables.ksh Files

When you log in to a Unix system at UVa, either the file named .profile (or .login for C shell users) or the file named .xinitrc will be run. The .xinitrc file is run if you log in using an X terminal. Each startup file will run other files (e.g. .variables.ksh or .xinitrc.ksh), which contain settings for the shell variables. You can modify these files to your preferences. Some sample files are shown below. These and other sample files are available for copying from the directory /help/unix/account.customization. Note that when a variable is preceded by a dollar sign ($), the current value of that variable will be used.

After changing your .variables.ksh file, you can activate it by executing it with the command

               . ./.variables.ksh

(This is done automatically if you logout and then log back in.)

Sample .kshrc File

The Korn shell provides the user with command aliasing, which is a way to rename a command along with your favorite options to a name of your choice. The ENV variable in the .variables.ksh file specifies the file $HOME/.kshrc. This means that the commands in $HOME/.kshrc will be read at each invocation of ksh.

ek
/PRE>

To see the current aliases, issue the command alias with no  parameters
To execute a new or modified .kshrc file, use the command

               . ./.kshrc

(This is done automatically if you logout and then log back in.)

To remove an alias from the current terminal session, use the command:

               unalias name



HOW TO USE COMMAND HISTORY

The Korn shell stores the commands you enter in a file named .history.
There  are  two ways to make use of the .history file to re-execute
commands you have previously typed.


First method:  Enter the command

               history

which will produce a list of the sixteen most  recent  commands  you
have  issued.   When  you locate the command you want to re-execute,
note the number of the command, and enter

               r command-number


Second method:  This method gives you the opportunity to  edit  your
previous command.

For Vi Users:  Put set -o vi in your .variables.ksh.  Then when  
you enter <ESC> (the escape key on your keyboard) followed 
by the letter k, the most recent command you have executed will 
appear on the command  line.  Repeating the letter k will present 
each command in the .history file in the order from the most recent.  
You are  going  up in the file.  By typing the letter j , you can 
go down in the file, provided you are not at the most recent command.  
The letter h moves the cursor one character to the left on the 
command line; the letter l moves the cursor one character to the right.
The  arrow  keys  do not work.

 
For JOVE Users:  Put set  -o  emacs in  your .variables.ksh  file.
(NOTE:  jove is not recognized as a command-line editor.)  To retrieve
commands, use Ctrl-p to bring back the most recently executed command.
After you have brought back at least one command, you can use the Control
key with various letters to move in different directions:  Ctrl-n to get
the next command, Ctlr-f to go to the right and Ctrl-b to go to the left.

For either editor:  
Once you have found the command you want to execute,  you can edit it
using some of the standard commands for the editor you use. See  the 
ksh man page for a complete  list of command-line editor commands.
When you have finished editing, enter a Return to execute the command.





JOB CONTROL

Background Jobs

To run any Unix command in the background so that you  can  continue
other work at your terminal, append an ampersand (&) to the command.  You
will immediately be returned to the system prompt so that you  can  issue
other commands.  The command jobs  will show you the 
status of your background jobs.

If you log out before the process has finished, it will  be  killed.
To avoid this, precede the command with nohup (no hangup). 
Its complete syntax is

               nohup command and arguments &

If that fails, try

               ksh

               nohup command and arguments &

               exit

If your command contains a pipe (|), issuing the command above  will  not
work.  Put the command into a file, make the file executable using chmod,
hen use its filename in place of command and arguments.

To lower the priority of your background jobs, use the nice  command
described  in  the  table below.  You can also specify a time to run your
job using the at command.  See the man pages on nice and 
at for more information and usage examples.

Finally, if you forget to put a lengthy job in the background,  Korn
shell  users  can  enter Ctrl-z to suspend the job.  Then enter bg to put
the job in the background; you will then get the system  prompt  so  that
you  can  do other work on the computer.  Similarly, if one of your 
background jobs seems to be running excessively and you suspect it  has  gone
awry,  issue  the jobs command to get the job number, 
then regain control of it by putting it into the foreground with fg
%job_number.   Then  you can terminate the job with Ctrl-c if you want.



Terminating Runaway Processes

Occasionally you may lose keyboard control  of  your  terminal.   If
this  happens, go to another terminal and log on to the same computer you
were logged on to when you lost control.  Issue the command:

               ps -fu login_id (RS6000, SGI, Solaris)

                    or

               ps -ux | grep login_id    (SunOS)

The screen (on an RS) for user abc3f with a runaway  session  might  look
similar to the figure shown below.

       UID    PID   PPID   C  STIME    TTY    TIME  CMD
       abc3f 34983 23462   0   May 08 pts/28  0:00  -ksh
       abc3f 43708 41403   0 15:51:47 pts/24  0:00  -ksh
       abc3f 54257 43708  40 16:07:52 pts/24  0:00  ps -fu abc3f


Each login session can be identified by a line ending in  "-ksh."   The
current  session  will be the one associated with the ps command (PID and
PPID 43708 in the listing above);  therefore, the runaway  session  above
has PID 34983.  Terminate the session by issuing the command

               kill -9 34983


 

 

 


Job Control Command Summary


Command
Result
                    
echo command_file | at time
run command_file at specified time
          
atq
list all at jobs belonging to user (for SGI use at -l)
                                                              
atrm id
remove at job with id (for SGI use at -r id)
bg [%job_number]
Put job_number in the background; default is

that has been suspended with Ctrl-z.
Ctrl-z
suspend current job
                     
fg %job_number
put job_number in the foreground
            
jobs
list background jobs
                        
kill -6 processID
Sends kill signal to process number processID, 

which is determined by issuing ps command.

Gives the process a chance to exit cleanly.
                                    
kill -9 processID
Terminates process number processID, which is

determined by issuing ps command.  Use with discretion.
                                  
nice command
Run command at lower priority; 

use for CPU-intensive programs.
                         
nohup command
No hang-up; use to keep a background job from

terminating at logout.
                     
ps [-eflu] or ps [x]
lists running processes (RS, SGI, Solaris)   

-e   show all processes                      

-f   full listing / show user ID             

-l   long listing                            

-uuser-id                                    

     show processes owned by user-id         

x    show processes with no controlling terminal (RS6000)
                             
ps [-alux]
lists running processes (SunOS)        

-a   show all processes                      

-l   long listing                            

-u   show user ID / full listing             

-x   show processes with no controlling terminal



As mentioned before, you can get complete information on  the  above
commands  by using the man command.  For job control commands specific to
the Korn shell (ksh) interface, type

               man ksh

for more information.



HOW TO GET HELP

The best sources of information (in addition to  this  document,  of
course) are:


The menu-driven help command.  Type help at the Unix prompt.
Call the Help Desk at 924-3731 between 8:00 A.M. and 5:00  P.M.  and
        ask to speak with a Unix consultant.
Send   electronic   mail  to consult@virginia.edu    (or 
        unix-consult@virginia.edu)   to   ask   a   question  via  e-mail  or  to
        suggest@virginia.edu to make a suggestion.
U-001, "Unix Resource List," which contains information  on  where
        to  get help (both on-line and written)  as well as a list of available
        software.
The command itcnews provides some on-line information about Information
        Technology  and  Communication  (ITC) and the services
        it provides.
The command hints accesses help pages in ITCWeb,
including documents and FAQs.
Standard Unix on-line documentation is available  for  all  commands
        using the man command.  Type 
man man at a Unix prompt for a description of the man command.


On the RS/6000s, there is an InfoExplorer program from  which  documentation
and  other  help can be obtained.  
You can run InfoExplorer by
just typing info.  If you are on a terminal that runs the X  Window  System,
   you may need to issue the following commands from an X window:

               xhost full-RS/6000-name

This will grant access to your display to any user on the RS/6000  specified.

               rlogin full-RS/6000-name

Complete the login process on the remote RS/6000.  Then enter:

               TERM=xterm

               DISPLAY=full-name-of-machine-running-X:0

To begin the InfoExplorer, enter the command:

               info



Appendix A: Printing Commands


The following chart includes some of the ways to send your output to
a  printer.  As for most Unix commands, output from a command can be sent
directly to a printer by using  the  "pipe"  to  redirect  the  output,
bypassing the need to place output into a file before printing it.

For example, you could send the output from the ls command directly to  a
printer with the command:

               ls | lpr

This is assuming that you have your PRINTER environment variable set. You
can  set  your  PRINTER  environment variable in your .variables.ksh with
PRINTER=printer_name.  Workstations in the Unix labs are set to print  to
the  printers in the labs (unless you specify a PRINTER or use the -P 
option, as shown below).




Printing Commands
Result
                     
enscript filename
send to Apple LaserWriter printer; many formatting  

options are available; see man page for   

complete information.
                                           
lpq -Pprinter
list print jobs for printer.
                   
lpr -Pprinter
send files to printer.
                         
lprm job_id
cancel print job job_id which is obtained      

from the lpq command.
                          
manpage command
send a copy of the manual page to default printer;     

printer can be specified with -Pprinter_name
                     
man printers
return names and locations of public printers  

on UVa's network.





Appendix B: Some Utility Commands
                                                                         


Utility Commands
Result
cal month year
return a calendar for month (digit 1-12)

and year (4 digits)
                                                                                   
calendar
read a file named "calendar" in your HOME    

directory containing dates and events; system  

sends daily reminders for current dates via    

electronic mail
                                                                                       
cut (-clist filename | -flist filename)
return list of columns or fields from filename
         
date
return date and time of day
                                                 
df
disk free; return available disk space in  

kilobytes (Sun) or i-nodes and kilobytes (RS/6000)
    
du directory
disk usage; return number of blocks used by directory
expand filename
replace each tab character in filename with spaces
file filename
show the type of a file (e.g., ascii,

directory, data, C program, etc.)
finger
return information on machine users
man [-k] command
return a copy of the manual page for command;

with -k, does a keyword search
paste file1 file2
concatenate corresponding lines of file1 and   

file2 by joining them with a tab character
                                     
namtest machine
return IP address of machine (RS/6000, Sun)
        
rlogin machine
log in to remote Unix machine
                       
script filename
copy all subsequent screen output to           

filename; type exit to end scripting
                                           
sort filename
sort filename in ascending order; 

many options available
                                                         
spell filename
return misspelled words
                             
stty
return terminal status; can be used to

modify terminal options                                                        
w
return who is doing what on the system
                      
whence command
search all the directories given in the PATH    

environment variable for the first occurance    

of command (Korn shell)
                                                   
who
list who is logged on to the system
                       
whois string
return information from UVa's database
 
 

   



Appendix C:  Setting File Permissions with Access Control Lists

NOTE:  Access Control Lists are not available on
the Unix cluster  blue.unix.virginia.edu.  Please look at the documentation for the Unix cluster for
alternatives.


On the RS/6000 computers and Suns running Solaris, there is  an  additional  method  for
setting  file  permissions  using an Access Control List.  This method is
useful to give file permissions to a specified group of users.

For example, if a research project leader  (user  "abc3f")  has  a
file  named  "research.part1"  located in his HOME directory to which he
wants several others to have write  permission,  he  could  follow  these
steps:


Step 1: Make the HOME directory searchable by other users with  the
command:

               chmod a+x ~

Step 2: Take away all permissions on  "research.part1"  from other  users
by issuing the following command:

               chmod og-rwx research.part1

Step 3: (AIX only) Give the list of research collaborators read and write permission
on the file by issuing the command:

               acledit research.part1

The acledit command uses the default editor for  the  system,  or
reads  the value of the EDITOR shell variable set by the user.  A
screen similar to the one below will appear:

                   attributes:
                        base permissions
                           owner(abc3f):  rw-
                           group(usr):  ---
                           others:  ---
                        extended permissions
                           disabled


Using editor commands, change the word under extended permissions
from  disabled  to  enabled  and  then add lines to make the file
similar to the one below:

                attributes:
                      base permissions
                         owner(abc3f):  rw-
                         group(usr):  ---
                         others:  ---
                      extended permissions
                         enabled
                         permit   rw-     u:login_1
                         permit   rw-     u:login_2
                         permit   rw-     u:login_3


where the actual login IDs for the research collaborators  appear
where login_1, login_2 and login_3 appear above.  Exit the editor
in the usual way.

Step 4: The acledit command will prompt with

           Should the modified ACL be applied? (y)


Answer with y or n as appropriate and the  process  is  complete.
Now the three collaborators can access the file.

Step 5: To give the same  access  control  list  to  another   file,  say
           "research.part2," issue the following command:

               aclget research.part1 | aclput research.part2

and all the permissions that are on  "research.part1"  will  be
copied to the file "research.part2."

For more information, see pages 364ff of AIX  General  Concepts  and
Procedures  for  the  IBM RISC System/6000 and the man pages for the
   commands acledit, 
aclget and 
aclput.



 

 

 

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