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Re: exit status issue


From: Stefano Lattarini
Subject: Re: exit status issue
Date: Wed, 23 Nov 2011 10:49:33 +0100
User-agent: KMail/1.13.7 (Linux/2.6.30-2-686; KDE/4.6.5; i686; ; )

On Wednesday 23 November 2011, Andreas Schwab wrote:
> "Steven W. Orr" <address@hidden> writes:
> 
> > I think we're beating this one to death, but I have point out that
> > telling perl to run a print command whose output is redirected by bash
> > is not the same as telling bash to run a builtin echo command that is
> > redirected as an integral operation of the same interpreter.
> 
> They are really the same, but even if you change it bash still wins:
> 
> $ bash -c 'echo "hello"' >/dev/full
> bash: line 0: echo: write error: No space left on device
>
IMO this is not really perl's fault, but rather the programmer's
fault, since he has forgotten to check for possible errors.  If
did, he would get:

  $ perl -e 'print "hello"; close(STDOUT) or die "$!\n";' >/dev/full
  No space left on device
  $ echo $?
  28

Something similar happens with C, of course, if you forget to check
error conditions:

  $ cat > foo.c <<'END'
  #include <stdio.h>
  int main (void)
  {
    printf("hello\n");
    return 0;
  }
  END
  $ gcc foo.c
  $ ./a.out >/dev/null # Oops, no error reported.
  $ cat > foo.c <<'END'
  #include <stdio.h>
  int main (void)
  {
    printf("hello\n");
    if (fclose(stdout) != 0)
      perror("Write error");
    return 0;
  }
  END
  $ gcc foo.c
  $ ./a.out >/dev/null # Error will be reported now.
  Write error: No space left on device

More "modern" languages, with built-in exception handling, are somewhat
better in this regard:

  $ python3 -c 'print("foo")' >/dev/full
  Exception IOError: (28, 'No space left on device') in ... ignored

Just my 2 cents.

Regards,
  Stefano



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