Essential DOS Commands
Essential DOS Commands and Concepts
IntroductionDOS (an acronym for Disk Operation System) is a tool which
allows you to control the operation of the IBM PC. DOS is software which
was written to control hardware. IDRISI, Atlas*GIS, Microstation,
AutoCAD, CPS/PC, and ARC/INFO are, in turn, application software which run under
DOS. By this we mean that, although IDRISI, Atlas*GIS, Microstation, AutoCAD,
CPS/PC, and ARC/INFO were written to accomplish a single task or application (in
this case manipulation of spatially related data), they must use DOS to pursue
its work.
DOS can be used for a wide range of tasks far beyond the requirements of this
class. You will be able to manage well if you master only a small subset of DOS
commands and functions. These relate almost exclusively to file and directory
management and are introduced in this handout.
This tip sheet assumes that you have learned how to turn on the PCs as they
are configured in room 230 and that you have familiarized yourself with their
keyboards (no small task in itself). It also assumes that you understand the
meaning of the concept of a file and the elements of a file specification
(drive, filename, and extension). The microcomputers you will be using are
equipped with two floppy disk drives. The A-drive is the 3.5" (1.44MB)
drive and the B-drive is the 5.25" (360KB) drive. The microcomputers also
contain a C-drive, a hard disk drive of 130MB or 200MB capacity.
You will quickly find that the best way to learn how to use a computer is
through experimentation. That is, once you have learned a command, try some
variations until they don't work, then start over. Often there are five or six
ways for you to accomplish a particular task. Usually, I will introduce you to
only one, leaving it up to you to discover the rest. Don't hesitate to consult
the DOS Reference Manual; copies can be found on the bookcase in room 230.
Finally, don't be unduly disturbed by error messages. With computers, one of the
best ways to learn is by making mistakes.
Most of the common DOS commands you need to use for this class (copy, rename,
delete) are available to you in Windows through the Filemanager icon. And, since
you can move back and forth between DOS and Windows, it doesn't matter which
option you employ. Some commands are faster in invoke in Windows, some in DOS.
If you haven't worked with Windows previously, go to the Windows tutorials in
the help area.
It is possible to lose files by mistake,
although the more you practice the less likely it becomes. For your own peace of
mind, it is good practice to make backup copies of your most valuable files on a
separate diskette. Store your backup disk in a safe place and don't carry it
through a metal detector. Use the COPY command to create the backup.
There is no need to backup every file you create, only the ones in which
you've invested much work. Also, prune your backup diskette every week or two
using the ERASE command. Backup files which have been made redundant by
subsequent additions will simply create clutter on your backup diskette. An
effective file naming convention is essential to keeping track of your backups.
To change the default
drive, simply type the letter of the your choice. The new default will be listed
in subsequent DOS prompts.
Example:
- C> A: [enter]
- Changes the default drive from C to A.
- A> C: [enter]
- Changes the default drive from A to C.
[enter] means that you must
press the Enter Key before the format command will execute. [Enter] is
required after any DOS command, it is assumed in all commands found below.
Once you have
located the directory you want, you may move from directory to directory using
the CD command (change directory)
Example:
- C> cd furniture
- Moves you to the directory called 'FURNITURE'
- C> cd \furniture\chairs
- Moves you to the directory called 'CHAIRS' under the directory called
'FURNITURE'.
- C> cd ..
- Moves you up one level in the path.
- C> cd \
- Takes you back to the root directory (c: in this case).
The COPY command can be used both to copy
files from disk to disk or to create a second copy of a file on a single disk.
(There are many more uses of the COPY command, but only the basic operation is
discussed here.)
Example:
- C> copy c:kermit.exe a:
- Copies the file 'KERMIT.EXE' from the C drive to the A drive and gives it
the same name.
- C> copy a:brazil1.dat b:\south\brazil2.dat
- Creates a copy of 'BRAZIL1.DAT' from drive A on drive B, putting it in the
'SOUTH' subdirectory and renaming it 'BRAZIL2.DAT'.
The key to use
this command correctly is to remember that the first file specified after the
COPY command is the source file, the second is the target:ehp1
file. The source is the file to be copied. The target will be the
location and name of the new file. If the file name and extension are omitted
after the target's drive specification, the new file will have exactly the same
name as the source file.
Example:
- C> copy a:myfile.txt b:
- C> copy c:command.com b:com.com
- C> copy b:golly.gee a:whao.boy
- C> copy command.* a:
- C> copy a:mymap.dwg c:\maps
Note: it is always good practice to
us the complete file specifications for both source and target files, Be very
sure of yourself before you accept defaults or employ wild-card characters.
Otherwise you may end up with some interesting results. Incomplete or incorrect
source names may result in errors, such as the command: copy edlin a:myomy.bat.
Try it and see what happens.
The DIRECTORY command lists the
names and sizes of all files located on a particular disk.
Example:
- C> dir a:
- Shows directory of drive A
- C> dir b:
- Shows directory of drive B
- C> dir \agis
- Shows files in a subdirectory on drive C (default)
- C> dir
- Shows directory of drive C
- C> dir /w
- Shows directory in wide format, as opposed to a vertical listing.
All the files are listed at the screen, you can stop the display by
typing CTRL-BREAK. If you ask for a directory on the A or B drives, be sure
there is a diskette in the drive and that the diskette has been formatted. If
the drive is empty, or if the diskette is unformatted, the DOS will respond with
an error message.
DIR OptionsTwo little characters, '*' and '?', will make your life with
computers much easier. Their use is illustrated below.
Example:
- C> dir a:*.ex
- Lists all files on the A drive with an extension of 'EXE'.
- C> dir b:kermit.*
- Lists all files on the B drive with a filename of 'KERMIT'.
The
asterisk is a wild-card character which allows the user to enter only a limited
part of a file specification to find a file. It is useful when you wish to
locate a group of files with the same filename or the same extension. On other
occasions you may have forgotten part of a file specification. You can use '*'
in place of the parts of the specification you have forgotten. Similarly, '?'
permits wild-card searches keyed to single characters.
Example:
- C> dir a:labe?.com
- Lists all five-letter files with the first four letters 'LABE' and an
extension of 'COM'.
- C> dir b:format.c??
- Lists all files with a filename of 'FORMAT' and an extension beginning
with 'C'.
Wild-card characters can be used in combination.
Example:
- C> dir a:labe?.*
- Lists all five-letter files with the first four letters 'LABE' and any
extension.
- C> dir c:*.ex?
- Lists all files with an extension beginning with 'EX'.
Experiment
with '*' and '?' to improve your ability to find files quickly. These wild-card
characters can also be used with several other DOS commands.
The ERASE command deletes specified
files.
Example:
- C> erase a:myfile.txt
- Erases the file MYFILE.TXT from the diskette in the A drive. If no drive
specification is entered, the system looks to delete the specified file form
drive C (in this case).
IMPORTANT WARNING: This command is easy to
use, but it is the most dangerous one you will encounter in DOS (apart form
FORMAT). If you aren't careful, you may delete a file which you--or someone
else--needs. And, unless you have saved a backup of that file, the erased file
is gone for good. For this reason it is good practice to use only complete file
specifications with the ERASE command (and to keep backups of your most valuable
files). As a safety precaution, never use the wild-card characters '*' and '?'
in ERASE commands.
BEWARE: I will rescind your laboratory privileges for a full week if you ever
knowingly use either the command: erase c:*.*, or the command: erase *.*. Guess
what happens?
Careful file naming can
save time. Always choose names which provide a clue to the file's contents. If
you are working with a series of related files, use a number somewhere in the
name to indicate which version you have created. This applies only to the
filename parameter; most of the file extension parameters you will be using are
predetermined (or reserved by DOS for certain types of file).
Example:
- WORLD.DAT
- An ATLAS*GRAPHICS file containing data for a world map. The DAT extension
is required by ATLAS*GRAPHICS.
- BRAZIL.BNB
- A boundary file of Brazil in binary form.
- BRIT1.DAT
- BRIT2.DAT
- BRIT3.DAT
- Three versions of a data file for a map of Britain.
You must format new disks before
using them on the IBM computers. The format command checks a diskette for flaws
and creates a directory where all the names of the diskette's files will
be stored.
Example:
- C> format a:
- Formats the diskette in the A drive.
- C> format b:
After entering this command, follow the
instructions on the screen. When the FORMAT operation is complete, the system
will ask if you wish to FORMAT more diskettes. If you are working with only one
diskette, answer N (No) and carry on with you work. If you wish to FORMAT
several diskettes, answer Y (Yes) until you have finished formatting all
your diskettes.
BEWARE: Executing the format command with a diskette which already contains
files will result in the deletion of all the contents of the entire disk. It is
best to execute the format command only on new diskettes. If you format an old
diskette make sure it contains nothing you wish to save.
This command creates
a new directory.
Example:
- C> mkdir mine
- Creates a directory called 'MINE'
In some cases,
when all attempts to recover from a barrage of error messages fails, as a last
resort you can reboot the computer. To do this, you press, all at once, the
control, alternate and delete.
BEWARE: If you re-boot, you may loose some of your work--any data active in
RAM which has not yet been saved to disk.
The RENAME command permits users
to change the name of a file without making a copy of it.
Example:
- C> ren a:goofy.txt pluto.txt
- Changes the name of 'GOOFY.TXT' on the A drive to 'PLUTO.TXT'.
This command is very simple to use, just remember two points: the file
name and extension must be complete for the source file and no drive
specification is given for the target. Renaming can only occur on a single disk
drive (otherwise COPY must be used).
This command
removes a directory. It is only possible to execute this command if the
directory you wish to remove is empty.
Example:
- C> rd mine
- Removes directory called 'MINE'.
If you wish to stop the
computer in the midst of executing the current command, you may use the key
sequence Ctrl-Break. Ctrl-Break does not always work with non-DOS commands. Some
software packages block its action in certain situations, but it is worth trying
before you re-boot.
Converted 20 July 1994. KEF.
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