Re: Re: vanishing system call

Hi
Thanks for the suggestions. There are a lot of helpful people here!
I tried to catch errors like this:

system(" cat $file | sort -t\\| +1 -2 > $file.out ") ||
  die "can't sort the file: $!";
[download]

... and I also tried $?. That's the creepy thing - it never even gets that far. It just skips the whole statement altogether.
I agree with your thoughts about virtual memory, and in fact this server has had some memory problems in the past. It just seems odd to me that I'm not getting some "out of memory" error (which I've seen before on this server) or even an out-and-out crash of the script. I need something to take to the Unix admins to convince them that there's a problem with the server (there are a number of production databases on there, so they won't reboot or anything like that w/o a good reason).
Oh, I forgot to mention that if I take the "sort" statement and put it in a separate Perl script, then run that to sort the file, it works fine. Which again leads me down the virtual memory path. In the short term, maybe I'll have to do the data processing and then the sort in two separate scripts, called up by a shell script or something. That's ugly but I'll bet it will work.
Thanks!

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Re: Re: Re: vanishing system call by sauoq (Abbot) on Sep 20, 2002 at 19:57 UTC
`system(" cat $file \| sort -t\\\| +1 -2 > $file.out ") \|\| die "can't sort the file: $!";` [download] Generally, system will return 0 when it succeeds not when it fails. That code would die everytime the system call worked. Update: As ChemBoy points out in his reply, `$!` is not what you want to look at. As I pointed out in a reply to another post of ChemBoy's, it only makes sense to look at `$!` when system returns -1 meaning that the command was not executed. This doesn't change the advice above. -sauoq "My two cents aren't worth a dime.";	[reply] [d/l] [select]
Error trapping from system by ChemBoy (Priest) on Sep 20, 2002 at 22:37 UTC
Nice catch on the return value of system--but in error cases, it doesn't set `$!`, but rather `$?`. Unfortunately, $? doesn't stringify nearly as nicely as $!, but you can get reasonable information (as outlined in perlvar) with a little extra work: `unless (0 == system $cmd) { warn sprintf "External command '%s' failed with exit status %d (sig +nal %d). A core dump %s\n", $cmd, $? >> 8, $? & 127, $? & 128 ? "occurred" : "did not occur"; }` [download] If God had meant us to fly, he would never have given us the railroads. --Michael Flanders	[reply] [d/l]