On Nov 22, 4:27 pm, carni...@gmail.com (Mark Wagner) wrote:
> I want to update a status file, similar to this:
>
> open OUTFILE, ">", "status.txt";
> print OUTFILE "$last_date\n";
> close OUTFILE;
>
> However, if something goes wrong (e.g. the disk is full), this code
> will replace "status.txt" with an empty file. How can I update the
> file while preserving the previous contents if something goes wrong?
>
> --
> Mark Wagner
Have you considered appending?
See an example below, with 2 successful status messages and 1 failed
one. The advantage of this is that you do not try to overwrite
anything - you just add. Note lexical filehandles and the use of
autodie to automatically check for errors.
$ rm -f status.txt
$ perl -e 'use autodie qw(:all); open my $status_fh, q{>>},
"status.txt"; print {$status_fh} scalar(localtime) . "\n"; close
$status_fh;'
$ cat status.txt
Tue Nov 22 18:22:29 2011
$ perl -e 'use autodie qw(:all); open my $status_fh, q{>>},
"status.txt"; print {$status_fh} scalar(localtime) . "\n"; close
$status_fh;'
$ cat status.txt
Tue Nov 22 18:22:29 2011
Tue Nov 22 18:22:44 2011
$ chmod a-w status.txt
$ perl -e 'use autodie qw(:all); open my $status_fh, q{>>},
"status.txt"; print {$status_fh} scalar(localtime) . "\n"; close
$status_fh;'
Can't open 'status.txt' for appending: 'Permission denied' at -e line
1
$ cat status.txt
Tue Nov 22 18:22:29 2011
Tue Nov 22 18:22:44 2011
$
HTH,
Timur Shtatland
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