Hi,
I often write frontends for commandline programs.
When I need their output, I call assignstream, when I don't I use shell.

What I would like however, is a way to check the exit codes of such programs, so that I can for example tell if a program failed to run correctly. Not all programs have output, and you cannot always get the output via assignstream, not to mention that you need to do a lot of string parsing to make sense of it when you do. This is not always easy, as you cannot always recognize every possible error message.

A system that can check wether the exit status was zero, and report and error if it wasn't would be much more ellegant
How could I ran another program from within my own, while detecting the exit code ?
I foresea something like this.

If runWithExitStatus('ls -alh')  0 then
Begin
	Writeln ('Error reading files');
	halt(1);
end;

If you use shell, you can only get the exit code of the shell (since that is the program that your program started). If you use Dos.exec(), use the DosExitCode() function afterwards. AssignStream doesn't seem to be able to return exitcodes.

Jonas

OK so shell is out, after all I am not all that concerned with how bash exited. Assignstream as well. I did not even know that dos exec could work under Linux, I somehow seem to think this is a less than adequate approach though.

How do C programmers do it under Linux ? I am sure it must be possible to use the same technique.

A.J.

A.J. Venter wrote

OK so shell is out, after all I am not all that concerned with how bash exited. Assignstream as well. I did not even know that dos exec could work under Linux, I somehow seem to think this is a less than adequate approach though.

The "dos" unit is simply an implementation of Borland's Dos unit, ie. it has the same interface, but the implementation is completely OS-dependent. There's nothing bad about using it under Linux or Win32. It doesn't allow you to capture the output of a program though. popen() (in the Linux unit) does, but I don't know whether it allows you to get the exit code. Check the documentation (units.pdf).

Jonas

It does if you use pclose() to close it the file.
The return value of pclose is the exit code of the program.

Michael.