What are external commands in DOS

MS-DOS basic course

MS-DOS (MicroSoft Disk Operating System) or IBM-PC-DOS is the most widely used operating system for IBM-PC / AT and compatibles. Currently Installed version (PC network): DOS 5.0 or DOS 3.2. New version: DOS 6.0 (DOS 6.2). Note: "Microsoft Windows" (Windows 3.1, Windows for Workgroups) is a graphical user interface with an extension of the MS-DOS operating system, but on which it is still based. Only "Windows NT" is an independent operating system.

System start (boot process)

when switching on (cold start) or restart (warm start). Restart with Reset Button (if available) or by pressing the key combination Alt + Ctrl + Del or Alt + Ctrl + Delete.

(1) ROM start program [ROM-BIOS: Basic Input / Output System]: a) reliability test (self-test, memory tests), b) initialization process, checking the equipment, c) calling up the bootstrap loader the boot entry on the floppy disk; this short program loads the floppy operating system (i.e. DOS).

(2) Loading from DOS. Required: special system disk (!) Or "bootable" hard disk. Basic components: IO.SYS (or IBMBIO.COM; BIOS, input / output routines) and MSDOS.SYS (or IBMDOS.COM; DOS routines) as hid Files and COMMAND.COM (command interpreter). Note: IO.SYS and MSDOS.SYS are permanently loaded into RAM, COMMAND.COM not (only partially). COMMAND.COM runs the internal Commands itself from (CD, CLS, COPY, DATE, DEL, DIR, ECHO, ERASE, MD, PATH, PROMPT, RD, REN, SET, TIME, TYPE, VER, VERIFY, VOL), calls external DOS commands from the disk / floppy disk (FORMAT FORMAT.EXE, PRINT PRINT.EXE, EDLIN EDLIN.EXE [line editor]) and searches for other programs (.COM, .EXE, .BAT) in the "search path" (PATH ).

Files, subdirectories

File names (e.g. or) consist of a maximum of 8 characters; optionally a period (.) and a extension of a maximum of 3 characters. Upper and lower case letters are not differentiated under DOS (!), So they are equivalent (in contrast to UNIX!). All information stored on floppy disks is in the form of Files (English: files ) managed. Attention: Storage space is always in Cluster reserved. Even a file that is only 1 byte long takes up 2048 bytes (= 1 cluster) on a 20 MB hard disk!

Principles of order

(a) Files can be on different Drives be (or will be) saved. Specification of the drive by the drive letters followed by a colon (:). Example: A: (first) floppy disk drive, B: second floppy disk drive, C :, D: hard disk (partitions), E: network disk,

(b) Subdirectories as "folders": This is located directly on a drive Main directory (Root directory). Because of its limited capacity and especially for reasons of clarity Subdirectories (English: subdirectories) created. Each subdirectory has a directory name that is created in the same way as a file name (see above); an extension is permitted, but is generally not used. Subdirectories can have further subdirectories (nesting). To form Pathnames subdirectory names and file names are separated from each other by a "backslash". Complete File identifier consist of:

Drive letter C: Path (= subdirectory [se]) \ TEXTE \ BRIEFE File name ANTRAG93 Extension .TXT File identifier C: \ TEXTE \ BRIEFE \ ANTRAG93.TXT

Notes: If only the file name is given (without path), DOS searches in the current subdirectory. (The directory can be changed with the CD command.) With some DOS commands (DIR, COPY, DEL) placeholder can be used in the file name: stands for any 1 character, stands for several (or even no) characters. Examples:

(copy all texts onto the floppy disk)
(delete the backup copies of the letters)

Executable programs have the extension .COM or .EXE (these need to be Start not to be specified; the same applies to batch files .BAT).

DOS commands: examples

DIR - "directory": Output directory
DIR * .TXT - list all text files
COPY C: \ TEXTE \ KAP1.TXT A: - copy the text "KAP1" onto the floppy disk
COPY A: *. * C: \ FOLDER -
copy the contents of the disk into the FOLDER directory
DEL * .BAK - delete all "backup copies"
REN ALT.NAM NEU.NAM - Rename the OLD file to NEW
MD CUNO - create a new subdirectory "CUNO"
RD CUNO - remove empty (!) Subdirectory
CLS - "clear screen": clear screen
FORMAT A: - Format floppy disk to 1.44 or 1.2 MB (HD)
FORMAT A: / 4 - Format floppy disk to 360 KB (for 5 1/4 ")
DATE - display or change the system date
TIME - display or change the system time
TYPE READ.ME - Listing of an "ASCII" file
PRINT READ.ME - Print an "ASCII" file
VER - shows the DOS version number
VOL - shows the name of the drive
CHKDSK - informs about disk usage

DOS: "Filter" commands

MORE stops the display after each page, e.g .:

Sort SORT (/ R backwards, / +n from column n ), E.g.:

(sorted by file size)

FIND search string (/ N with line number, / C only number of hits, / V Not included), e.g .:

(including all * .BAT files)

(find "text" in an ASCII file)

DOS: Redirection of input or output

(how )

> serves to redirect the output, e.g. to the printer (prn):

(how )

>> also redirects the output, appending the text to an existing file.

Equipment: CON (terminal), PRN or LPT1 (printer), COM1, COM2, (RS232: serial interfaces).

DOS: display / change system parameters

SET display or change system parameters.

(here is the DOS command interpreter)

(Search paths for commands and programs)

("System prompt", here; $ p path, $ g>, $ d date, $ t time)

DOS: Batch files ("batch files", * .BAT)

are summaries of (any) DOS commands in (ASCII) text files. AUTOEXEC.BAT (in the main directory) is automatically executed when the system is started (after CONFIG.SYS has been processed).

Special DOS commands for batch files:

(or) Commands are (not) displayed
Display of text on the screen
Jump command
Jump destination (preceded by: colon), must appear as a separate line
condition command conditional statement
Jump if the file exists
(with error message 1)
(Parameter 1 = Surname ?)
(% 1 stands for the first transfer parameter,% 2 for the second etc .; note the doubled = character; the X here only serves as a protective measure in the event that no parameter was transferred)
Repetition. E.g.:
causes:
Comment line

Burkhard Kirste; 1993/11/17