[Linux-disciples] Opening the wrong file

[Adam Kessel]

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On Thu, Nov 13, 2003 at 10:56:39AM -0500, Stephen R Laniel wrote:
> Is this easy to do?

No.  I don't think there's any easy way to detect where the input is
coming from.  After all, a pipe redirects standard input from a file.

The better way to do what you want would be:

zcat /var/log/apache/access.log.10.gz |~/log -

I believe that will accomplish your goal without having to change your
perl code.

=2E..
> I just noticed a bug in a little Apache-log post-processing script that I
> wrote. If the user specifies an input file on the command line
> ('log [filename]'), the script opens that input file; otherwise the
> script defaults to opening /var/log/apache/access.log. The relevant chunk
> of code is
>=20
> my $logfile =3D (@ARGV ? $ARGV[0] : '/var/log/apache/access.log');
> #[...]
> open( STDIN, "<$logfile" )
> 	or die "Could not open $logfile.\n";
>=20
> The trouble I just noticed is that if I try to use syntax like
>=20
> zcat /var/log/apache/access.log.10.gz |~/log
>=20
> it doesn't work: the script doesn't recognize that a file has been piped
> in, so it uses /var/log/apache/access.log.
>=20
> Is there a way to fix this? The logic I want is
>=20
> * if a file's been piped in, use that.
> * if a file's been specified on the command line, use that.
> * if both a pipe and a file have been specified ... figure out this
>   case at some other time
> * if neither a pipe nor a file have been specified, use
>   /var/log/apache/access.log.
>=20
--=20
Adam Kessel
http://bostoncoop.net/adam

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