Re^3: system and $?

rovf,
I have never set $! in a program to set the exit status - I have always used exit for that.

#!/usr/bin/perl
# ... rest of program
exit(0); # assuming everything went according to plan
[download]

Does that not work on windows?

Cheers - L~R

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Re^4: system and $? by rovf (Priest) on Aug 26, 2009 at 13:19 UTC
I have never set $! in a program to set the exit status Of course you don't set $! to set the exit status!! You set $! to zero before a call to system(), in order to clear it. If system returns no error, but $! is set afterwards, you know that there must have been an error indeed. If you would not clear $! before the call to system(), you would not know afterwards whether there was an error in system(), or in some earlier function. For example, in the two following cases (on my platform), system returns the same value in both cases, and $! is also set in both cases, although only the first system() call actually failed: `# On Windows 2000, ActiveState Perl 5.8.8 or 5.10 # case one: opendir(FOO,'.'); system('this_program_does_not_exist'); # $? == 256, $! != 0 # case two: opendir(BAR,'this_directory_does_not_exist'); system('perl -e "exit 1"'); # $? == 256, $! != 0` [download] But if you explicitly reset $!, you can distinguish between those cases: `# On Windows 2000, ActiveState Perl 5.8.8 or 5.10 # case one: opendir(FOO,'.'); $!=0; system('this_program_does_not_exist'); # $? == 256, $! != 0 # case two: opendir(BAR,'this_directory_does_not_exist'); $!=0; system('perl -e "exit 1"'); # $? == 256, $! == 0` [download] -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re^5: system and $? by Limbic~Region (Chancellor) on Aug 26, 2009 at 13:22 UTC
rovf, Mea Culpa! I misunderstood and responded after only glancing at your reply before running off to a meeting. That'll teach me to drive by reply. Cheers - L~R	[reply]