Programming Forums > Application Development > C++

Lakrids · Jun 9th, 2008, 3:47 PM

Thanks! But does this mean that on UNIX based systems, in cases where you don't have to do anything (or have to wait) for the child to terminate, it is wiser to use system() than doing

 c Syntax (Toggle Plain Text) 
pid_t pid = fork();
if (pid==0) {
    exec(...)
}
else if (pid != -1) {
    wait(status);
}
pid_t pid = fork();
if (pid==0) {
    exec(...)
}
else if (pid != -1) {
    wait(status);
}

because for one, it is shorter to write

, and second, it is cross-platform (which is pretty much my aim)?

grumpy · Jun 9th, 2008, 4:30 PM

Given that command shells (the things executed by system() on unix variants, as an intermediary to executing your string) vary between flavours of unix, and also with whims of system administrators or end users (eg selection of different shells), the action of system("some_string") varies a lot. It is often better to KNOW the results of code, than to rely on system behaviour that can change without your control.

Sorrofix · Jun 9th, 2008, 5:42 PM

Quote:

Originally Posted by grumpy

That is only true on some target platforms, and with some libraries. It is not a predictable result.

The C standard has this to say on system(), and is all that can relied upon in cross-platform development.

I stand corrected.

Jun 9th, 2008, 3:47 PM	#11
Lakrids Newbie Join Date: Dec 2007 Posts: 28 Rep Power: 0	Re: Cross-platform exec() Thanks! But does this mean that on UNIX based systems, in cases where you don't have to do anything (or have to wait) for the child to terminate, it is wiser to use system() than doing c Syntax (Toggle Plain Text) pid_t pid = fork(); if (pid==0) { exec(...) } else if (pid != -1) { wait(status); } pid_t pid = fork(); if (pid==0) { exec(...) } else if (pid != -1) { wait(status); } because for one, it is shorter to write , and second, it is cross-platform (which is pretty much my aim)?

Jun 9th, 2008, 4:30 PM	#12
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,209 Rep Power: 5	Re: Cross-platform exec() Given that command shells (the things executed by system() on unix variants, as an intermediary to executing your string) vary between flavours of unix, and also with whims of system administrators or end users (eg selection of different shells), the action of system("some_string") varies a lot. It is often better to KNOW the results of code, than to rely on system behaviour that can change without your control.

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Programming Forums > Application Development > C++

Cross-platform exec()