Re: Need help re: System Calls

[kst@sd.aonix.com (Keith Thompson)]

In <1997Apr12.220404.1@eisner> kilgallen@eisner.decus.org (Larry Kilgallen) writes:
[...]
> I understood "spawn" from this discussion to provide access to a CLI,
> but what is valid from that point on certainly varies between
> operating systems, and as I understand it, even between Unix
> variants.  In general it would seem that portability of access
> to "system" capabilities is not helpful between domains where
> those capabilities are not identical.

By the way, the system() function is part of the ISO C standard, so it's
very likely that you can use the features of Annex B to invoke it in a
nearly portable manner if there's a C library available on your system.

Here's the definition (typos mine):

    7.10.4.5 The system function

    Synopsis
	#include <stdlib.h>
	int system(const char *string);

    Description
    The system function passes the string pointed to by string to
    the host environment to be executed by a command processor in an
    implementation-defined manner.  A null pointer may be used for string
    to inquire whether a command processor exists.

    Returns
    If the argument is a null pointer, the system function returns nonzero
    only if a command processor is available.  If the argument is not a
    null pointer, the system function returns an implementation-defined
    value.

Of course, the interpretation of the parameter is entirely
implementation-defined.  On a Unix or Unix-like system, it's typically
passed to some version of the Bourne shell (/bin/sh).

-- 
Keith Thompson (The_Other_Keith) kst@sd.aonix.com <http://www.aonix.com> <*>
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