Unix Tutorial
- File and Directory Structures - Recommended structures for your design work
- Using a UNIX Terminal Window - Setting up a UNIX shell
- Some Basic UNIX Commands - Useful UNIX commands
- The Common Desktop Environment - Features and facilities of the UNIX desktop
Author: Jeff Ormerod
File and Directory Structures
To utilise the applications software successfully you will need a basic grasp of how files and directories are organised on the CAD server.
The following diagram illustrates a typical structure for a Bolton Institute student.
The top level directory (given the symbol / ) is referred to as the root directory. Under this are a number of other directories defining areas where the UNIX operating system software is held (e.g. bin, usr), the applications software (e.g. cad) and user directories (e.g. rb1ele, mh5ele).
At any point in time you will be located at a particular level in the directory structure. This is your Working Directory. When an account is created, a user directory is created with the same name as your account name. This is referred to as your Home Directory and will be your working directory at log in.
Directories and files have a pathname from the root directory so for a user with the account name rb1ele the pathname of the home directory would be:
/students/rb1ele
You can create any number of files and directories downwards from your home directory. In the example above a design directory cadencework and two design directories assignment and walkthroughs have been created by user rb1ele. Typically as applications software is invoked and a design proceeds, a number of additional directories and files will be created automatically by the software. Again in the example above, the CADENCE software has created a further directory schematics, two files cds.lib and cds.log and two more files sheet1 and sheet2 inside schematics.
The pathname of the file sheet2 would therefore be:
/students/rb1ele/cadencework/walkthroughs/schematics/sheet2
Using a UNIX Terminal Window
UNIX provides a comprehensive set of commands for interacting with the operating system and manipulating files and directories.
All commands are entered into the system via a Terminal Window.
Typically one Terminal Window will be present at log in.
To open another Terminal Window or to create one if one doesn't exist:
There are a number of potential routes:
Using the Desktop Menu
If you move the mouse cursor over the desktop background and use the right hand mouse button the context sensitive menu will be displayed.
If you look in the "Tools" submenu you will see a menu entry for "Terminal" displayed. Selecting this option will open up a terminal.
Using the menu bar at the base of the UINX window
Click on the arrow above the CPU and Disk icon ( currently third from the right) on the CDE toolbar.
Now click on the "This Host" option to open the window.
Do not use a "Console" window as this has a specific purpose on the UNIX systems and will not give you the same results as a termainl window.
Commands are typed after the operating system prompt ($) and entered by pressing the Return key. UNIX is case sensitive and requires that all commands are entered in lower case.
The example terminal window below shows the response to entering the UNIX cal command which displays the calendar for the current month.
Some Basic UNIX Commands
The following sections identify some useful commands together with associated practical exercises that you can try if you are unfamiliar with the UNIX operating system.
Directory Related Commands
| Command | Description |
| pwd | Display the pathname of the present working directory |
| mkdir | make directory |
| ls | list a directory contents |
| cd | change directory |
| mv | move (and rename) a directory |
| cp | copy a directory |
| rm | remove a directory |
Exercises in Directory Management
Enter the following commands in order in a terminal window and observe
their effect.
Commands with more than one component (e.g. cd / ) require a
space between each component.
| Command | Description |
| pwd ls |
Displays the pathname of your current
working directory. If you have just logged on this will be your home
directory. Lists the contents of this directory |
| cd / ls |
Changes directory to the root directory.
This is now your new working directory. The '/' addition to the
cd command is a quick way of moving to the root from anywhere in the
system Lists the contents of this directory. Here you will see subdirectories for the operating system, user accounts and applications software |
| cd pwd ls |
Changes back to your home directory.
The cd command issued by itself will always set your working directory
to your home directory from anywhere in the directory structure Displays the pathname of this directory Lists the contents of this directory |
| mkdir test ls |
Creates a subdirectory called test
inside your home directory Lists the contents of your home directory. You will now see the newly created directory test added to the listing |
| cd test pwd touch testfile ls |
Changes into the test directory Displays the pathname of this directory Creates an empty file called testfile Lists the contents of this directory. The one file testfile will be listed |
| cd .. pwd ls |
Changes back up one level to your home
directory. This is accomplished by the addition of the '..' to the cd
command. The command can be extended to move up any number of levels
e.g. cd .. /.. will move up two levels Checks that the current working directory is now your home directory Lists the contents of this directory |
| cp -r test project mv test design ls |
Creates a copy of the test directory
named project. The '-r' (recursive) option enables all subdirectories
and files within a directory to be copied Renames the test directory as design Lists the directory contents. Directories project and design will be added. |
| rm -r project design ls |
Deletes the directories project and design. The
'-r' (recursive) option enables all subdirectories and files within
a directory to be deleted. Lists the directory contents. There should now be no entry for directories project or design. |
File Related Commands
| Command | Description |
| touch | Create a file or modify a file's date/time stamp |
| cat | catenate (display) the contents of a file |
| more | Display a large file in sections |
| cp | copy a file |
| mv | move a file |
| rm | remove a file |
Exercises in File Management
Enter the following commands in order in a terminal window and observe
their effect.
| Command | Description |
| cd mkdir calendar cd calendar touch cal.dat ls |
Changes to your home directory Creates a directory called calendar Moves into directory calendar Creates a file called cal.dat Lists the directory contents with file cal.dat added |
| cal 2001 > cal.dat cat cal.dat more cal.dat |
Executes the calendar command for the
year 2001 and writes the information to the file cal.dat. The symbol
'>' is used to redirect the output of the command from the display to
a file Displays the contents of file cal.dat Displays the first section of the file cal.dat. Continually press the spacebar to display more of the file |
| cp cal.dat cal1.dat mv cal.dat cal2.dat ls rm cal2.dat ls |
Copies file cal.dat to a new file called
cal1.dat Renames the file cal.dat to a new file called cal2.dat Lists the directory contents. It will contain files cal1.dat and cal2.dat Deletes file cal2.dat Lists the directory contents. It will contain only file cal1.dat |
Use of Pathnames in Directory and File Management
Application packages such as Cadence generate deep directory structures.
Occasionally it becomes necessary to move, copy, rename or delete files
between directories. Using pathnames in the directory and file management
commands enables other directories to be modified from the current working
directory. Here are some examples.
| Command | Description |
| ls ../ ls ../.. ls /students/mp3/project ls cadence/design |
Lists the contents of the directory one above the
current working directory Lists the contents of the directory two above the current working directory Lists the contents of directory /students/mp3/project Lists the contents of the directory design within the directory cadence in the current working directory. Note the omission of the '/' symbol at the beginning of the pathname when going down from the working directory. |
| cp test.vec ../test.vec cp test.vec ../project/test.vec cp test.vec /students/mp3/project/test.vec cp test.vec design/test1.vec |
Copies file test.vec to the directory
one above the current working directory Copies file test.vec to the directory project in the directory one above the current working directory Copies file test.vec to directory /students/mp3/project Copies file test.vec as test1.vec to the directory design in the current working directory |
| mv test.vec ../test.vec mv test.vec ../project/test.vec mv test.vec /students/mp3/project/test.vec mv test.vec design/test1.vec |
Moves file test.vec to the directory
one above the current working directory Moves file test.vec to the directory project in the directory one above the current working directory Moves file test.vec to directory /students/mp3/project Moves file test.vec as test1.vec to the directory design in the current working directory |
| rm ../test.vec rm ../project/test.vec rm /students/mp3/project/test.vec rm design/test.vec |
Deletes file test.vec in the directory
one above the current working directory Deletes file test.vec in the directory project in the directory one above the current working directory Deletes file test.vec in directory /students/mp3/project Deletes file test.vec in the directory design in the current working directory |
Other Useful UNIX Commands
| Command | Description |
| ls -la | Provides a full directory listing with file/subdirectory dates, times, access rights etc. |
| ps | Lists all the processes active in your session. Each process has a name and a Process Identification (PID) number |
| kill -9 PID | Terminates a process with a particular PID. For example kill -9 1234 will terminate the process whose PID is 1234. The '-9' option will kill any process regardless of type. This command is useful if an applications package locks up |
| man command | Provides help information on a particular command. For example man ls will list all the uses of the ls command |
The Common Desktop Environment (CDE)
The Common Desktop Environment toolbar provides a number of functions you will find useful when running applications software.
The Text Editor
The Text Editor can be used to create a new file or read/edit an existing file.
Click on the Notepad and Pencil icon to open up the Text Editor
To create a new file select File - New from the editor toolbar to open up the Text Editor
To read or edit an existing file select File -Open from the editor toolbar to display the Open a File menu as shown below
Scroll down the Folders list to locate the required directory. You can double click on a directory entry to move down into its subdirectories or the '..' entry to move up to the parent directory. Double click on the required file in the Files list to display the selected file in the Text Editor.
File - Save on the editor toolbar will save the file. A new file will require a filename specifying in the Enter file name: box of the Text Editor - Save As menu and an appropriate destination directory selected from the Folders list. An existing file will automatically be saved in its current location.
More information on the features and facilities of the Text Editor can be obtained by selecting Help on the Text Editor toolbar
File - Close on the editor toolbar will close the Text Editor
The File Manager
The File Manager enables you to see your directory structure and manipulate directory and file entries. It provides a graphical alternative to using the UNIX file and directory commands.
Click on the Filing Cabinet icon next to the calendar to open a display of the directories and files in your home directory as shown below
Directories are denoted by folder icons
Files are denoted by text icons
Executable files are denoted by yellow ziz-zag icons
You can display the contents of a directory by double clicking on its icon
You can display the contents of a file in the Text Editor by double clicking
on its icon
You can move up into the parent directory by double clicking on the ..(go
up) icon
You can move a file or directory from one directory to another as follows:
Open up the File Manager and select the required source directory
Open up a second File Manager (select the filing cabinet icon again) and
select the destination directory
Click on the required source entry and check that it highlights
Now drag the entry from the source directory to the destination directory
You can copy a file or directory using the same procedure as for the move but hold down the Ctrl key whilst dragging the entry from source to destination
You can delete a file or directory by selecting the required entry and pressing the Delete key
More information on the features and facilities of the File Manager can be obtained by selecting Help on the File Manager toolbar
Select File - Close on the File Manager toolbar to close the File Manager
The Workspaces
The CDE provides four workspaces identified on the toolbar with default names One, Two, Three and Four
They enable four customised desktops to be defined. This is particularly useful when you have a number of application packages running (e.g. Netscape and Cadence) and wish to keep their associated windows separate or a time consuming activity (e.g. simulation) during which you wish to do other work.
The default workspace is One. Click on each of the other workspaces in
turn and observe that they define separate desktops with different backgrounds.
You can open up Terminal Windows, issue UNIX commands, run applications
software, call up the File Manager and Text Editor from any workspace
You can also rename each workspace to indicate more accurately the activity
you intend to use it for.
Simply double click on the workspace name, type in the new name and press
Return
Each of the workspaces can also be customised for colour scheme and background
by clicking on the Mouse, Pallette and Ttt icon on the toolbar.
This will open up the Style Manager. Click on the Help option on the Style
Manager toolbar for further information
Comprehensive information is available on all the CDE facilities by selecting the Book and Question Mark icon on the toolbar.
Updated 10.10.05 RA Updated 22 02 07 NC