Disk Operating System (DOS)

The syntax and usage of selected DOS internal commands, including: TIME, DATE, CLS, DIR, COPY, TYPE, DEL, REN, RD, MD, CD, PATH, and SET PROMPT.

DOS Internal Commands

The DOS (Windows 9x) internal commands are so-called because their instructions are a part of COMMAND.COM, the DOS (Windows 9x) command processor.

Recall that COMMAND.COM is placed into memory each time the DOS or Windows 9x OS is booted. Therefore, the internal commands are always in memory and can always be executed from any command line prompt.

This is in contrast to the disk-bound external commands, which reside in secondary memory up until the moment they are needed, at which time the OS must find them and load them into primary memory.

The syntax for some frequently used internal commands follows.

TIME
Displays current time and allows it to be changed.
Syntax: TIME DATE
Displays current date and allows it to be changed.
Syntax: DATE CLS
Clears the screen.
Syntax: CLS DIR
Shows directory information of a diskette: name, size, and the date and time stamp of files.
Syntax: DIR [d:][path]
Optional switches:
/p Display dir info and pauses display when the screen is full
/w Display names and extensions only in five columns

To display a file directory listing for D:\DATA\LETTER\ANNUAL from different current directories:
D:\DATA\LETTER\ANNUAL> DIR
D:\DATA> DIR LETTER\ANNUAL
C:\WINDOWS> DIR D:\DATA\LETTER\ANNUAL
COPY
Copies a file. Name of copy may be the same as original, or different. Syntax: COPY [d:][path][name.ext] [d:][path][name.ext]
Optional switches:
/v Verify, copies the file and compares it with the original
/b Binary file

To copy a file from D:\BATCH to the root of A: drive A:\> COPY D:\BATCH\CL.BAT (from A: drive)
D:\BATCH> COPY CL.BAT A:\ (from D:\BATCH)
To copy a file from the root of C: to A: drive and change its name A:\> COPY C:\MSDOS.SYS MSDOSSYS.BAK (from A:)
C:\> COPY MSDOS.SYS A:\MSDOSSYS.BAK (from the root of C:)
To copy all of the files from the root of A: to D:\CCV\ENGCOMP A:\> COPY *.* D:\CCV\ENGCOMP (from A:)
D:\CCV\ENGCOMP> COPY *.* A:\ (from D:\CCV\ENGCOMP)
TYPE
Displays the contents of a file.
Syntax: TYPE [d:][path][name.ext]

To display the contents of the file MY.LET to the screen
A:\> TYPE MY.LET
DEL
Deletes a file from disk.
Syntax: DEL [d:][path][name.ext]

To delete one file: A:\> DEL A:\MY.LET To del all files in current directory A:\> DEL *.*
REN
Renames a file.
Syntax: REN [d:][path][name.ext] [d:][path][newname.ext]

To change the name of the file D:\LET\ANNUAL\99.DOC to 1999.DOC D:\LET> REN ANNUAL\99.DOC 1999.DOC (from D:\LET)
D:\DATA> REN \LET\ANNUAL\99.DOC 1999.DOC (from D:\DATA)
C:\WINDOWS> REN D:\LET\ANNUAL\99.DOC 1999.DOC (from C:\WINDOWS)
MD
Makes (creates) a new directory.
Syntax: MD [d:][path][dirname]

To create a directory named HERMIT in the root of D: drive D:\> MD HERMIT (from D:\)
C:\> MD D:\HERMIT (from C:\)
RD
Removes an existing directory (directory must be empty).
Syntax: RD [d:][path][dirname]

To remove the HERMIT sub-directory: D:\> RD HERMIT (from D:\)
C:\> RD D:\HERMIT (from C:\)
CD
Changes the current directory.
Syntax: CD [path][dirname]

To make D:\HERMIT the current directory D:\> CD HERMIT (from D:\)
D:\DATA> CD \HERMIT (from D:\DATA)
D:\DATA\SOURCE> CD \HERMIT (from D:\DATA\SOURCE)
D:\DATA\SOURCE> CD .. (from D:\DATA\SOURCE)
PATH
The PATH command is used to help the command interpreter find external commands which are not in the current directory. The command interpreter looks into the
DOS environment for "PATH=" and then searches the paths (each separated from the next by a semicolon) that follow.
Syntax: PATH=[path;path;...]

To set the DOS PATH: PATH=C:\DOS;C:\PCW;\C:\BIN To display the current path: PATH
SET PROMPT
Used to specify the appearance of the DOS prompt.
Syntax: SET PROMPT= (from the command line)

PROMPT= (in a batch file)

      DOS PROMPT Characters
      $b    |                      $d   system date
      $e    esc char               $g   >
      $h    destructive bk space   $i   <
      $n    default drive          $p   full path description
      $q    =                      $t   system time
      $v    DOS version no         $_   CR and LF
      $$    the $ sign

To display current drive & current path followed by ">" as prompt SET PROMPT=$P$G To display the current date, time, and drive on separate lines SET PROMPT $D$_$T$_$N$G To redefine F9 to CD\Windows\Start Menu\Programs\Startup SET PROMPT $e[0,67;"'CD\Windows\Start Menu\Programs\Startup'";13p

Bruce Miller, 2002