Unix Commands Summary

Fall 2002

Last updated November 05, 2002

Accessing your Unix account from another system

• use SSH  (get from http://www.uidaho.edu/info-security/ssh)
• use Putty
• use CRT
• telnet unix.uidaho.edu or telnet comp-sci.cs.uidaho.edu
  

Unix commands

Logging in to and out of your account

• To log in to your Unix account enter your username and / or password as requested by the system.  What you are asked to enter depends on which communication program you are using to access your account (see previous bullet).
  
• Once you have successfully logged in to your account you will see a command line prompt that will look something like this:
      raptor:/users/w/wjones>
  
• Unix commands are case sensitive and most are entered by typing lower case letters.  After entering the command press the <enter> key.
  
• To log out of your Unix account, at the command line prompt type:  exit
      Example:  raptor:/users/w/wjones>exit
  

• The Unix directory structure looks like this:
  
                         /                            <Slash is top directory>
                      users      ………….  
             w                             x    …………
      wjones               ………                         <Home level>
  cs112      misc                                     <account subdirectories>
  
  

  • .. points up one level
  • . points to current level
  • File names and directory names are case sensitive.  Avoid creating file or directory names with embedded spaces in the name.
    
• The current working directory is shown in the command line prompt of many Unix systems.  In the example below the current working directory is is cs112 which is a directory within the home directory of the account wjones.
      Example: raptor:/users/w/wjones/cs112>
  
• To change the current working directory directory
  • Change to specific directory:  cd <directoryname> 
    Example:  raptor:/users/w/wjones>cd cs112
  • Moves up one level:  cd ..
  • Move to home directory:  cd
  • Move to the system root directory: cd /
    
• To find out what the current working directory is type pwd at the command line prompt
      Example: raptor:/users/w/wjones/cs112>pwd
  
• To generate a list of the files and directories contained in the current directory, at the command line prompt type:
  • List directory (short):  ls
  • List all files in directory:  ls –a   
  • Long list:  ll   

• Help is provided by the unix command man.  Man is short for manual.  Man is not a very sophisticated help system.  You must know the name of the command for which you desire help.  To get help on a Unix command type:  man <command name>
      Example:  raptor:/users/w/wjones/cs112>man ls
  will produce many pages of output on your screen describing what the ls command does and what arguments or options it supports.
  
• While in man you can enter the following commands to control what happens:
  
  • Advance 1 line:  <return>  
  • Advance 1 page: <space>
  • Quit: q

Manipulating files and directories

• Copying files
  To copy file 1 to file 2 at the command line type:  cp <filename1> <filename2>   
     Example:  raptor:/users/w/wjones>cp Prog1.cpp Prog2.cpp
  
• Moving or renaming a file
  To move or rename a file at the command line type:  mv <filename1> <filename2>
     Example: raptor:/users/w/wjones>cp Prog3.cpp Prog4.cpp  
  
• Deleting or removing a file
  To remove or delete a file at the command line type:  rm <filename>
     Example:  raptor:/users/w/wjones>rm Prog1.cpp    

• Make / create a new directory:  mkdir <directoryname> 
  Example:  raptor:/users/w/wjones>mkdir cs112Programs 
   
• Remove / delete the directory:  rmdir  <directoryname>
  Example:  raptor:/users/w/wjones>rmdir cs112Programs
  

Viewing contents of a file on the console:

• Lists top few lines of a file:  head <filename> 
     Example:  raptor:/users/w/wjones>head Prog1.cpp  
  
• List last few lines of a file: tail <filename>
     Example:  raptor:/users/w/wjones>tail Prog1.cpp  
         
• List file and allows up/down movement:  less <filename>  
     Example:  raptor:/users/w/wjones>less Prog1.cpp      

• List file one screen at a time from the top:  more <filename>
     Example:  raptor:/users/w/wjones>more Prog1.cpp 
  
• Display / listing / dumping / print the entire contents of a file to the console display:  cat <filename>
      Example:  raptor:/users/w/wjones>cat Prog1.cpp 
  

• At the command line type: script <filename>
       Example:  raptor:/users/w/wjones>script myconsole.txt
  
• Everything that is type on or printed to the console will be echoed (saved) to the designated file.
  
• To end the capture operation, at the command line type: exit
      Example:  raptor:/users/w/wjones>exit
  
• Caution:  There is no visual clue that tells you if script is actively logging your console.  If it is not, and you type exit, you will terminate your session.
  
• Warning:  Do not attempt to display the script log file on the console while script is actively logging the console.

Retrieving previously typed commands and file names:

• Instead of typing a command over, at the command line prompt type <esc>-k.  This will fill in the command line with the last command you typed.  Typing <esc>-k again will bring up the command previous to the first.  If you go too far you can type <esc>-j  to back up.
  

• When you are entering a command (e.g., g ++) that requires a file name, you can retrieve the name of an existing file to be inserted into the command.  At the command line prompt type the command you want to execute and one or more letters that begin the desired file name followed by <esc> <esc>.  This will fill in the rest of the name, if there is a file name that matches.
  

Pico Editor

To invoke the Pico editor, at the command line prompt type:  pico <filename> where <filename> is the name of the file you want to create or an existing file you want to edit (modify):
    Example:  raptor:/users/w/wjones>pico Prog1.cpp

To save the file you have just created or modified type <ctrl>-o (control-o), then press enter.  Before you press the enter key you have the chance to change the name of the file that will be written.

To exit pico type: <ctrl>-x (control-x)

C++ Compiler

To compile the program that you have created with the pico editor, at the command line prompt type:  g++ <filename>
Example:  raptor:/users/w/wjones>g++ program1.cpp

If your program compiles without errors the compiler produces a.out in the same directory.  a.out is the executable file.

Executing and Terminating a Program:

Executing a program:

To execute the program that you have successfully compiled type, at the command line prompt type:  ./a.out

Terminating an executing program or Unix command:

To terminate the execution of a program (maybe it's not responding for some reason) or to terminate the execution of some unix command your can type <ctrl>c.  <ctrl>c means that you hold down the Ctrl key and the c key simultaneously. 

FTP (File Transfer Protocol)

FTP is used to move files from one computer to another.  When you are logged on to your ITS Unix account and want to get a file from the public FTP site in the CS Department where I place some program test files you need to use FTP.  The following digest of an FTP session is similar to what you should see on your console.  The lines shown in blue are either Unix prompts or FTP prompts and the text shown in bold is what you need to type.  The rest of the lines are ones produced by the FTP program.  Your output may differ slightly from what is shown in the following:

falcon:/users/w/wjones>ftp ftp.cs.uidaho.edu
Connected to lucky.cs.uidaho.edu.
220 lucky.cs.uidaho.edu FTP server (Version 1.1.214.4(PHNE_23950) Tue May 22 05:49:01 GMT 2001) ready.
Name (ftp.cs.uidaho.edu:wjunk): anonymous
331 Guest login ok, send your complete e-mail address as password.
Password:
230 Guest login ok, access restrictions apply.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /usr/bin/ls.
total 10
dr-xr-xr-x 3 root root 4096 Oct 15 2001 bin
dr-xr-xr-x 3 root root 4096 Oct 15 2001 etc
dr-xr-xr-x 29 root root 4096 Nov 1 10:42 pub
dr-xr-xr-x 4 root root 4096 Oct 15 2001 usr
-r-xr-xr-x 1 root root 344 Jun 15 1994 welcome.msg
226 Transfer complete.
ftp> cd pub
250 CWD command successful.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /usr/bin/ls.
total 5
drwxr-xr-x 2 261 root 4096 Oct 23 2001 cs101.karen
drwxr-xr-x 2 262 root 4096 Nov 4 09:48 cs112BillJunk
drwxr-xr-x 3 261 root 4096 Apr 25 2002 cs112kvh
drwxr-xr-x 3 282 root 4096 Oct 15 2001 cs113
226 Transfer complete.
ftp> cd cs112BillJunk
250 CWD command successful.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /usr/bin/ls.
total 4
-rwxr-xr-x 1 262 100 446 Nov 1 14:32 File1.dat
-rwxr-xr-x 1 262 100 0 Nov 1 14:33 File2.dat
-rw-r--r-- 1 262 100 404 Nov 4 09:48 File3.dat
226 Transfer complete.
ftp> get File1.dat
200 PORT command successful.
150 Opening BINARY mode data connection for File1.dat (446 bytes).
226 Transfer complete.
446 bytes received in 0.03 seconds (15.31 Kbytes/s)
ftp> bye
221 Goodbye.