Wednesday, 17 April 2013

Dos Command

Dos

Some Important DOS Command Reference
Introduction:
Many course material on the Teaching Network may still use the command line operating system called DOS (Disk Operating System). This requires the user to type specific commands at a prompt. You may also need to use this system, for example, when changing your password, and you can enter DOS by choosing 'MS-DOS Prompt' from the Public menu on the taskbar.

Command Format:
 Commands can be typed in response to the network DOS prompt:
G:\>
Commands may be typed in upper or lower case. Here, they are specified in upper case to distinguish them from other input. Commands have a particular format.Some can be used
simply by typing the command name only, as in:
DIR
which displays a listing of files in the current directory.

Parameters: 
Many commands can take extra information called parameters to make them more specific, For example, the  COPY command can have a parameter specifying a file to be  copied and a parameter specifying a file to which the copy is to be made. So the command would look like this:
COPY filea fileb
In this case, filea would be the name of a file to copy from and fileb would be the name of a file to copy to. Parameters can sometimes be omitted in which case a default
action will apply.

Options: 
Commands can also be qualified by the use of options. Options are preceded by a / sign. A simple example of the use of an option is with the DIR command. 
DIR can be qualified by /P or /W. Thus the commands:
DIR
DIR  /W
DIR  /P
result in listings presented in a different format as detailed later.

Some Useful DOS Commands:
COPY --  Make a copy of a file or merge files together.
COPY original-file destination-file
where original-file  and destination-file  are file names, separated by a space.
The command can be used to merge several files into one file since the original-file parameter can be a list of  filenames separated by the + symbol. For example:
COPY file1  + file2 file3
would copy file1 and file2 into file3.
Note that the file names used in the copy command must
include the file extension if it exists. So if you were copying a fortran program called first.for, for example, you would need to include the .for extension in the filename.

DEL -- Delete a file.
DEL filename
where filename  is the name of the file to be deleted. You are  asked to confirm that you really want to delete the file. Note that the name must include the file extension. The amount of space on a disk is limited and it is necessary periodically to tidy up unwanted files. It is possible to use a '*' character in a filename to match any sequence of characters.
This feature is   very useful when deleting unwanted files with identical extensions. For example, when developing programs,
DEL  *.obj
will delete every binary (.obj) file in the current directory.
Since an  .obj  file can always be recreated from the original source program, it is usually unnecessary to keep it.

DIR: 
Obtain a list of the files stored in a directory. If used without options this command will give a list of files in the current directory, including any extension (e.g. .for), and their size. If used with the option /P, that is:
DIR  /P
The same information will be displayed page by page with the message:
strike a key when ready
at the end of each page.
If it is used with the /W option, i.e.
DIR  /W
the listing is of names and extensions only and in a more compact format across the page.

DISKCOPY:
 Take a security copy of your working disk. It is very important to have a second copy of your programs and data in case you lose your disk or it becomes unreadable for some reason. Use the DISKCOPY command as follows:
DISKCOPY A: A:
where A: denotes the drive the disks will be loaded into. When  a copy of your disk is generated in the computer's memory, the computer tells you to remove the first or source disk and insert the disk, which is to become the copy (the target disk).

Insert the target disk and press ENTER. If the second disk is  not formatted it will be formatted automatically. The source disk should be write protected using the tab in the corner in case you mistake it for the target disk (see the chapter on using disks).

LIST:
Obtain a printed listing of a file. LIST filename where filename is the file to be printed. If the printer is busy, or if you don't need a printed copy, you can use the TYPE 
command to view a file on the screen. You could also use an editor such as DOS Edit to display a file, in which case, as a bonus, you would then be in a position to correct any errors you might notice. Remember that the file name must include the file extension. So if you want to print  your Pascal program called first you would need to use:
LIST first.pas

RENAME:
Change the name of a file. This command can be abbreviated to REN:
REN oldname newname
where oldname is the file to be renamed and newname is the name it is to be given. Note that files on drives other than the current drive can be referred to by prefixing the filename by the relevant drive letter, for example:
A:\filename
where the \ refers to the ‘root’ directory of the drive
Filenames can also include directories separated by the \ character as in:
A:\dir1\dir2\filename

TYPE:
View a file on the screen. TYPE filename where filename is the name of the file to be displayed on the monitor screen. If you are looking at a long file, you will need  to press the PAUSE key to stop continuous scrolling. Press the  space bar to continue scrolling when you have read the screen.

FORMAT:
To format a floppy disk, place the disk in the floppy drive and type FORMAT A:
Note that by default the disk will be formatted to hold about 1.44
megabytes of data.
Warning: formatting will destroy any data on the disk so only
do this once!

DOS Command Listing:
In the following section, alternative options are separated by the ‘!’ character. Arguments are optional unless in italics. ‘cwd’ stands for ‘Current Working Directory’.


DOS Conventions:
DOS commands are not case sensitive. Some commands have switches; these must be preceded by a forward slash (/). Pathnames may be precedd by a drive letter as in ‘X:pathname’ and if no drive or pathname is given the current

directory is assumed.

The Commands:
ATTRIB +!-r +!-a pathname
Display, or set!clear Read-only or

Archive attribute

BREAK on!off

display, or turn on!off increased level of ^C detection

CHDIR (CD) path

display, or change working directory

CHKDSK pathname   (A: drive only)

check disk or file logical structure

/f          - fixproblems encountered

/v         - verbose; displays filespecs

CLS clear screen


COMMAND path cttydev

run nested CLI from path with I/O device cttydev

/e:#              - set environment size #

/p                     - do not invoke another CLI

/c command - run command and then enter

COPY pathname   pathname

or

COPY pathname + pathname 
                
copy or concatenate files

/v         - verify writes

/a!b      - preceding and all subsequent files are ascii!

binary (* filenames in source(s) and target are matched

one-to-one.)

CTTY device

change MS-DOS I/O device

DATE dd-mm-yy

display and/or set date (numerical country-dependent format)

DEL ! ERASE pathname

delete file(s) - prompts if pathname is *.*

DIR pathname

display directory - filename and/or ext default to *

/p         - paginate

/w        - multi-column

DISKCOPY drive: drive:

copy disk sector-by-sector rather than file-by-file

EXIT

exit nested CLI

FIND “string” pathname

find and display lines containing string in file

/v         - lines NOT containing string

/c       - count lines only

/n       - display line numbers also

FORMAT drive:   (A: drive only)

/1         - single sided

/4         - use double rather than high density (40 tracks)

/8         - use 8 sectors of each track

/n:xx   - specifies xx sectors per track

/t:yy     - specifies yy tracks

/v         - prompt for volume label, up to 11 characters

/f:720   - format at 720 kb

LABEL drive: label   (A: drive only)

display, or edit volume label - 11 characters excluding

most specials

MKDIR (MD) path

make directory
MODE

interactively configure various options

MORE

paginates screen output

e.g. type filename | more

PATH path;path;...

display or set command search path(s) to be used after

cwd

PATH;

resets default to cwd only

PROMPT string

reset or set prompt.

Characters (each prefixed by $) mean:

$=$, t=time, d=date, p=cwd, v=version, n=drive,

g=>, l=<, b=!, _=CRLF, s=leading space, e=ESC (for ANSI driver)

RENAME (REN)pathname pathname

rename file(s) within a drive - wildcards are matched

one-to-one

RMDIR (RD) path

remove empty directory

SET variable=text

display all, set or clear MS-DOS variable - accessed as %variable%

SHARE

enable networked multi-access file locking

/f:nbytes - nbytes per file, need about 20 bytes per file,

default 2048

/l:nlocks - nlocks per file, default 20

SORT pathname pathname

sort lines of file alphabetically, ignoring case, to file or stdout; reads stdin by default

/r       - reverse order

/+n      - on n’th character in each line, default is first

SUBST drive: path   (A: drive only)

display substitutions, or substitute path by virtual drive

SYS drive :   (A: drive only)

copy hidden MS-DOS .sys files from default drive

TIME hours:minutes

display and/or set time using 24-hour format

TYPE pathname

output contents of a file, with tab spacing of 8

VER

display MS-DOS version

VERIFY on!off

display, or set!clear disk write verification

VOL drive:

display disk volume label


XCOPY pathname pathname 
            
copy directory tree

/a!m    - if archive bit set ! also clears in source

/d:date- modified on or after date only

/s!e        - copy subdirectories if not empty ! even if empty

/p           - prompt

/v           - verify

/w        - wait for keypress

If renamed to MCOPY it determines automatically whether

target is file or directory.

On-Line Command Help:
Full details of all DOS commands can be seen by following the command with the switch /? For example,

DIR /?

gives a listing of all DIR options.


Command Editing:
DOS commands are stored in a template and previous commands can be recalled, character by character enabling editing as required.


The template is accessed by the following keys:-

F1        -           get next character from template

F2 C    -           get characters up to but excluding character C

F3        -           get remaining characters from template

del       -           skip one character in template

F4 C    -           skip characters up to but excluding character C

ESC        -           clear command line

INS         -           toggle overwriting of template

F5        -           copy command to template for re-editing

F6        -           put ^Z in new template

The arrow keys may also be used to recall the previous

command.


Batch File Commands:
All DOS commands may be used in batch files. Additionally, the following commands are useful for more advanced batch processes.


Arguments for batch files are accessed as ‘%1’ to ‘%9’.

ECHO on!off!message

display echo status, turn echoing on!off (default on)

or display message

FOR %%C IN (SET of items) DO command

C is any character other than 0-9, SET is e.g. list of files


GOTO LABEL

LABEL is any line of text, usually preceded by colon (:)

in first column, which makes MS-DOS ignore it other than as a label. Terminates if label not found

IF ERRORLEVEL number command

command executed if previous command returned exit

code >= number

IF string1  == string2 command

command executed if strings match

may be negated by NOT before condition

IF EXIST filename command

command executed if file exists

may be negated by NOT before condition

PAUSE comment

comment displayed only if echo on

REM comment

remark - ignored by MS-DOS

SHIFT

shift arguments - allows access to more than 9


SpcialCharacters:
Several special characters may be used when referring to

directories and files:

\          =          root directory or a directory separator

=          current directory

=          parent directory

Wildcard characters may be used in filenames or extensions:

?           =          any character

*          =          any tail or extension

X:         -           switches to current working directory (cwd) on

drive X.


File Comparison Utility:
The FC command enables comparison of two files:

FC pathname1 pathname2

compare two files, or two wildcarded sets of files

/a         - abbreviate output of ASCII comparison

/b         - force binary comparison (byte-by-byte)

/c       - ignore case

/L         - force ASCII comparison (line-by-line)

/Lb#     - use line buffer of # lines

/n       - display line numbers in ASCII mode

/t          - do not expand tabs - default expands to spacing

of 8

/w      - compress white space (tabs and spaces) to

single space (leading or trailing white space

always ignored)

/#       - # lines must match to re-synchronize else

regarded   different (default is 2)


I/O Control
DOS input and output may be controlled by the following control key sequences.   (^ = the CTRL key).

^C       -           abort current command

^H       -           destructive backspace

^J        -           linefeed - physical newline to input long lines

^N       -           toggle copying of terminal output to printer

^P        -           toggle redirection of terminal output to printer

^S        -           suspend/restart terminal output

^X       -           cancel current line, and output \-CR-LF

^Z        -           end of file


I/O Redirection   
Input and output from commands or programs can be

redirected by using the following symbols:

>          send output to...

>>     append output to...

<          take input from...

|          pipe output to next input


Example:

pipe output from command a to input of command b:

command a | command b

send a directory listing to file filename:

DIR > filename

Using The DOS Editor:
DOS includes a full-screen editor invoked by the EDIT  command (with or without a filename). To use this editor type:

EDIT (filename)

The editor provides pull-down menus, operated by the keyboard or mouse, and a help facility. Note that any changes made to a file overwrites the original, no backup is created...

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