Introduction to Unix (HPUX)

Introduction to UNIX

What is HP-UX?

HP-UX is Hewlett-Packard Company's implementation of Unix. It is based on AT&T UNIX* System V Release 2 operating system, but also includes important features from Berkeley Software Distribution 4.2.

The UNIX shell and the Kernel

The kernel is the heart of the UNIX operating system. Usually only programs talk to the kernel (through system calls). As users, we talk to the shell. It is the shell which interprets our commands and either executes programs or requests other services from the kernel. There are several shells available; the one generally used on our system is called the KORN shell (ksh). When you wish to interact with the the shell, you must exit from the menu provided at login. When finished using the shell, typing exit will either return to the menu where you can Quit, or if you do not currently have a menu, will log you off the system.

The UNIX File System

The UNIX file system is very similar to that of MS-DOS. It is organized hierarchically into directories for efficient organization.

A directory is simply a special type of file - it is a file which contains a list of files. After logging in, the home directory assigned to you becomes your current working directory. To change the current working directory us cd.

Path Names are used to refer to files not in your current directory. Path names tell the system where files are located. Full (absolute) path names begin with /, which is the name of the top or root directory of the whole file system. After the initial / comes the name of each subdirectory followed by a /, until finally the file name is reached (e.g. /users/able1234/mail/saved-messages).

Relative paths are more convenient because they are shorter, but must be used with care. They never begin with /. For example to refer to a file in my mail subdirectory, when I am in my home directory, I can simply start with the name of the subdirectory (e.g. mail/saved-messages).

Useful Directory Commands

Although a directory is simply a list of files, there is a special command to display the contents of a directory.

   ls     lists the contents of a directory (except for system files)
   ls -a  lists all the contents of a directory, including system files
   ls -l  same as ls with additional information
   ls -lt same as "ls -l" except the list is sorted by time modified 
          (latest first)

To change directories, use cd.

   cd mail   changes to your mail directory
   cd ..     changes to the directory immediately above the current
             working directory.

To display the full path to the current working directory, use pwd.

To list the subdirectories in the current working directory the following command is useful: ls -d */. (the period is important)

To create a new subdirectory use mkdir (e.g. "mkdir foobar").

Displaying the Contents of a File on the Screen

Any text file can be displayed with several utilities or it can be edited with an editor like pico or vi. If it is a long file the command more will scroll the contents, pausing after each screen (e.g. "more mail/sent-mail"). If you don't care about the pauses, use cat (e.g. "cat mail/sent-mail"). ("cat" is derived from "conCATenate") To actually modify or create your mail signature file you would use pico (or vi) (e.g. "pico .signature").

Printing a File

Any text file can be printed with the lp command. For example, if you wanted to print a file named resume to the printer in the LeMans PC Lab, you would use the command

    lp -dlmpc5simx resume

Useful File Commands

To rename a file, use mv (e.g. "mv .signature .signature.old"). To copy a file, use cp (e.g. "cp file1 programs/file1"). The first filename given is the one being copied, the second filename will be the one created by the copy command. To delete a file, use rm (e.g. "rm junk").

Changing Your Password

The UNIX command to change your password is passwd. For more information on the password command, see the on-line Passwords Guide

UNIX Manual Pages

The full HP-UX Manual describing any command is accessible from the UNIX shell using the "man" command.

man - find manual information by keywords: 

SYNOPSIS
	man -k keyword (produces a one-line entry for all commands 
			whose one-line description contains the keywords)

	man command ... (for the full description of the command)

Examples
	Show the manual entry for the lp command
	
		man lp

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