Date: Sat, 7 Apr 2007 20:11:20 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Olivier Regnier <oregnier@steelbox.org> Cc: freebsd-questions@freebsd.org Subject: Re: script perl with sed command Message-ID: <20070407171120.GA70957@kobe.laptop> In-Reply-To: <4617B954.7010507@steelbox.org> References: <4617B954.7010507@steelbox.org>
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On 2007-04-07 17:31, Olivier Regnier <oregnier@steelbox.org> wrote:
> Hello,
> I have a problem with my perl script with the command sed. Here is a
> example of my code:
Don't use system("sed ...") in Perl. It's considered poor style, since
Perl can do the same without having to fork a shell/sed process.
> # Selecting the fast server
> print "Using the server called $server";
> system(`/usr/bin/sed 's|\*default host=\(.*\)|\*default host=${server}|'
> $standard_supfile > $standard_supfile.copy`);
> system('/bin/mv $standard_supfile.copy $standard_supfile');
Try using Perl only, instead of forking sed(1), like this:
,-----------------------------------------------------------------------
|
| #!/usr/bin/perl -Tw
|
| use strict;
|
| #
| # supfile_set_default_host($supfile, $newhost)
| # Set the default host used by the supfile $supfile to the
| # host name supplied as $newhost.
| #
|
| sub supfile_set_default_host($$);
| sub supfile_set_default_host($$)
| {
| my $tmpsupfile;
| my $supfile = shift;
| my $newhost = shift;
|
| if (!defined($supfile) || !defined($newhost)) {
| return undef;
| }
|
| $tmpsupfile = "tmp-" . $supfile;
| open(SUP, "$supfile") or die "$!";
| open(TMP, "> $tmpsupfile") or die "$!";
|
| my $line;
| while (defined($line = <SUP>)) {
| chomp $line;
| $line =~ s/^(\*[ \t]*default[ \t][ \t]*host[ \t]*=).*/$1${newhost}/;
| print TMP "$line\n";
| }
| close(TMP) or die "$!";
| close(SUP) or die "$!";
| rename("$tmpsupfile", "$supfile") or die "$!";
| return 1;
| }
|
| supfile_set_default_host('standard-supfile', 'cvsup.example.net');
|
`-----------------------------------------------------------------------
This is slightly more complex than forking a sed(1) utility run, but
it's easier to understand (at least it is for me).
A very brief run of the script seems to work here:
,-----------------------------------------------------------------------
|
| $ pwd
| /tmp
| $ cp /usr/share/examples/cvsup/standard-supfile .
| $ grep 'default host' standard-supfile
| *default host=CHANGE_THIS.FreeBSD.org
| $ perl -Tw supfile.pl
| $ grep 'default host' standard-supfile
| *default host=cvsup.keramida
| $
|
`-----------------------------------------------------------------------
- Giorgos
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