DOS Commands in Assembly 1

[spudnuts]

Simple question, how do I execute a dos command (i.e. COPY, XCOPY, DIR, DEL, etc) in assembly. I have a good grip on using DOS interupts but lost on how to call and execute a dos command within an assemply program.

Information Assurance,CCNP,CST

 

[spudnuts]

BTW,

I'm using A86.

Information Assurance,CCNP,CST

 

[earthandfire]

You would need to use Int 21h Function 4B00h (AX) to execute an external program, set DSX and ES:BX as appropriate.

XCOPY.EXE is independent program, whereas COPY, DIR and DEL are internal commands. To run these pass CMD.EXE as the program and the relevant command as the command tail.

For DIR C:\ you would use CMD.EXE (don't forget to include the full path) and /C DIR C:\ as the command tail. The /C switch tells CMD.EXE to execute the following command and then terminate.


An undocumented DOS Interrupt - as least as far as DOS 6, INT 2Eh takes a standard COMMAND.COM command line in DS:SI and runs the command. This may or may not work in a windows DOS box - it didn't always work under DOS and may not be compatible with CMD.EXE


Hope this helps.

 

[LoLevelPrgmr]

You probably will also have to release some memory that your program does not require for the int 21 / 4B00 function to work. Look on the web for Ralf Brown's interupt list for more info.

Another way to do DOS commands would be to use a couple of batch files. Write the commands you want the PC to do into one file -say JOBS.BAT. Have the main bat file do something like this:

LABEL: asmprogram.exe
call JOBS
goto LABEL

This assumes that your asm program can save enough state info to be restarted and know what it needs to do next.

Later.