topic Re: check to see if multiple files exist in Operating System - Linux

check to see if multiple files exist

Rahul_13 — Fri, 11 Aug 2006 14:16:09 GMT

I have written a perl script in which I need to check if files exist in a directory and then remove them from that directory.

I am doing the following:

my @arr = `ls \directory\file*`;

my $arr_cnt = $#arr +1;

if ($arr_cnt > 0)
{
foreach (@arr)
{
unlink($_);
}
}

This works fine if there are files in the directory but retuns an error message that no file exist in that directory if that directory does not have files of the specified pattern.

I know that I cannot check if multiple files exist with the file test.

Can anyone help.

Thanks,
Rahul

Re: check to see if multiple files exist

Marvin Strong — Fri, 11 Aug 2006 14:29:59 GMT

seems like overkill for perl to me but

if (scalar(@arr) > 1) { do something }

that should tell you if you have multiple items in your array.

Re: check to see if multiple files exist

A. Clay Stephenson — Fri, 11 Aug 2006 14:30:10 GMT

You just need to redirect stderr of your ls.

my @arr = `ls \directory\file*`;
becomes:
my @arr = `ls \directory\file* 2>/dev/null`;

Re: check to see if multiple files exist

James R. Ferguson — Fri, 11 Aug 2006 14:31:11 GMT

Hi Rahul:

#!/usr/bin/perl
my @arr = glob "/path/file*";
unlink for (@arr);

Regards!

...JRF...

Re: check to see if multiple files exist

James R. Ferguson — Fri, 11 Aug 2006 14:38:53 GMT

Hi Rahul:

The 'glob' is a Perl built-in, so it's faster than invoking an external 'ls'.

That aside, there is no need to test for the number of array elements --- the 'foreach' (or shorter 'for') iterates over the array (or list) until there are no more elements. If there are none to begin with, the loop terminates immediately.

Regards!

...JRF...

Re: check to see if multiple files exist

James R. Ferguson — Fri, 11 Aug 2006 16:54:50 GMT

Hi Rahul:

Actually, we can eliminate iterating over the list; pass it in it's entirely to 'unlink'; count the number of files removed; and print that summary in one short piece of code. For example:

# perl -e '$n=unlink glob("/tmp/*.log");printf "%d file%s unlinked\n", $n, $n==1 ? "":"s"'

Regards!

...JRF...