how to execute a programme within a programme ?

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March 31st, 2003, 08:18 AM

Jonas_G

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how to execute a programme within a programme ?

How do I execute a programme within a C programme ?
any good docs articles on this ?

March 31st, 2003, 09:17 AM

dwise1_aol

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Quote:

NAME
system - execute a shell command

SYNOPSIS
#include <stdlib.h>

int system(const char *string);

DESCRIPTION
system() executes a command specified in string by calling
/bin/sh -c string, and returns after the command has been
completed. During execution of the command, SIGCHLD will
be blocked, and SIGINT and SIGQUIT will be ignored.

RETURN VALUE
The value returned is -1 on error (e.g. fork failed), and
the return status of the command otherwise. This latter
return status is in the format specified in wait(2).
Thus, the exit code of the command will be WEXITSTA-
TUS(status). In case /bin/sh could not be executed, the
exit status will be that of a command that does exit(127).

If you are using a DOS/Windows C compiler, it should also have implemented system(). Just read the help file/documentation on it.

When you use system(), the calling process is still there and can check the status returned by the system() call.

However, if you want to have the called program replace the calling program, then look into the exec* family of functions.

March 31st, 2003, 05:34 PM

Jason Doucette

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I recall reading a few weeks ago that the system command is VERY slow. Be sure to read the documentation like dwise1_aol suggested. I think it provides an alternative.

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March 31st, 2003, 07:39 PM

dwise1_aol

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The man page on Linux also mentions some gotcha's regarding signals, I think. It didn't apply to what I was doing, so I didn't pay much attention.

And don't just read the documentation, but also write some test code.

May 20th, 2003, 05:03 PM

ComputerGuy356

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You can use shell execute to run a program from within a program. For documentation, visit http://msdn.microsoft.com/library/d...hellexecute.asp

ShellExecute(NULL,
"open",
"C:\\Program Files\\Internet Explorer\\iexplore.exe",
NULL,
NULL,
SW_SHOW)

May 20th, 2003, 07:57 PM

infamous41md

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jason i noticed u said system is very slow? what about execve?

May 20th, 2003, 08:46 PM

dwise1_aol

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Quote:

Originally posted by infamous41md
jason i noticed u said system is very slow? what about execve?

In both Windows and Linux, execve would replace the calling program. In Linux we'd couple it with a fork, but Windows doesn't do forks -- there's CreateProcess which works quite differently.

However, Jason_G never replied, so we don't know what OS he's running or whether exec* would work for him or not.

how to execute a programme within a programme ?

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