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How to capture DEBUG output when using DOS
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- Ian! D. Allen - idallen@idallen.ca - www.idallen.com

This is a step-by-step explanation of the use of input and output
redirection in DOS.  You might find this useful when saving the output
of DEBUG into a file (or files).

  * Suppose I want to capture the DEBUG output of dumping the boot sector.
  * (You choose the DEBUG commands that you need to execute.)
  *
  * To dump the boot sector, here's what I would normally type into DOS
  * and DEBUG, along with the expected output:

C:\>
C:\> DEBUG
-L 0 0 0 1
-D 0 L 20 
2C4B:0000  EB 45 90 22 22 79 6F 3D-49 48 43 00 02 02 01 00   .E.""yo=IHC.....
2C4B:0010  02 F0 00 34 08 F0 04 00-0E 00 02 00 00 00 00 00   ...4............
-Q
C:\>

  * I don't want this DEBUG output on my screen; I want it in a file,
  * so that I can have it for printing or incorporating into my
  * assignment when I reboot my computer and restart Windows.
  *
  * Just like Unix (from which it was copied), DOS supports input and
  * output redirection on command lines.  So I type this output redirection:

C:\>
C:\> DEBUG >OUT

  * At this point, everything that would normally appear on my screen
  * is being sent into the file named OUT in the current directory.
  * (You can use any pathname to put the output anywhere you want.)
  * 
  * Now, when I say *everything*, I mean *everything*.  That means
  * anything I type won't echo on my screen, it's going to go directly
  * into the file OUT.  So I can't see what I'm typing.  I have to
  * type "blind" and hope I don't make any mistakes.  So I type the
  * same three lines I typed above.  They don't echo on my screen (I'm
  * typing blind, with no keyboard character echo at all):

L 0 0 0 1     *** BLIND TYPING: this line does not echo on my screen ***
D 0 L 20      *** BLIND TYPING: this line does not echo on my screen ***
Q             *** BLIND TYPING: this line does not echo on my screen ***
C:\>

  * The moment I type Q and hit return, DEBUG exits, just as it did
  * above.  I look in the output file to see the echo of what I typed,
  * along with the expected output from DEBUG:

C:\>
C:\> TYPE OUT
-L 0 0 0 1
-D 0 L 20 
2C4B:0000  EB 45 90 22 22 79 6F 3D-49 48 43 00 02 02 01 00   .E.""yo=IHC.....
2C4B:0010  02 F0 00 34 08 F0 04 00-0E 00 02 00 00 00 00 00   ...4............
-Q
C:\>

  * I must have blind-typed the lines correctly - it looks correct.
  *
  * So that's one way to save output from DEBUG into a file; but, I don't
  * like the fact that I can't see what I'm typing.
  * 
  * DOS also supports input redirection.  That means I can prepare a file
  * containing my typed commands and feed that file as input to DEBUG.
  *
  * So I will prepare a text input file containing my three DEBUG command
  * lines.  I use the DOS "EDIT" command to do this.  EDIT supports the
  * arrow keys so that I can move around and edit text.  When I want to
  * exit, I push ALT-F to bring up the File menu, and I use the arrow keys
  * (or I type x) to select "Exit".  It asks me where to save the file,
  * and I type in a file name such as "INPUT".
  *
  * After creating the INPUT text file with EDIT, I type my input text
  * file on the screen to make sure it is correct:

C:\>
C:\> TYPE INPUT
L 0 0 0 1
D 0 L 20
Q
C:\>

  * Those are the three commands I want DEBUG to execute.
  * (Don't forget the Q (QUIT) command as the last line!)
  *
  * I first select only DOS input redirection, so that I can see the
  * output from DEBUG on my screen:

C:\>
C:\> DEBUG <INPUT
-L 0 0 0 1
-D 0 L 20 
2C4B:0000  EB 45 90 22 22 79 6F 3D-49 48 43 00 02 02 01 00   .E.""yo=IHC.....
2C4B:0010  02 F0 00 34 08 F0 04 00-0E 00 02 00 00 00 00 00   ...4............
-Q
C:\>

  * DEBUG read my three commands from the file INPUT and displayed the
  * output on my screen - I didn't have to type anything.
  *
  * Since I'm happy with that output, I redo the same command but this
  * time add output redirection to save the output in a file called OUT:

C:\>
C:\> DEBUG <INPUT >OUT
C:\>

  * No input was needed from me - it all came from the INPUT file.
  * No output is visible - it all went into the OUT file.
  *
  * I check the contents of the output file OUT:

C:\>
C:\> TYPE OUT
-L 0 0 0 1
-D 0 L 20 
2C4B:0000  EB 45 90 22 22 79 6F 3D-49 48 43 00 02 02 01 00   .E.""yo=IHC.....
2C4B:0010  02 F0 00 34 08 F0 04 00-0E 00 02 00 00 00 00 00   ...4............
-Q
C:\>

  * That's correct.
  *
  * I repeat variations on this process until I have all the output files
  * I want for my assignment.  For small commands, I type blind and
  * just redirect the output.  For more complex things, I use EDIT to
  * prepare a list of commands that I want DEBUG to execute for me.

-- 
| Ian! D. Allen  -  idallen@idallen.ca  -  Ottawa, Ontario, Canada
| Home Page: http://idallen.com/   Contact Improv: http://contactimprov.ca/
| College professor (Free/Libre GNU+Linux) at: http://teaching.idallen.com/
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