Stephen Kratzer wrote:
> On Thursday 10 July 2008 05:59:36 Anirban Adhikary wrote:
>> Dear list
>> I want to capture the output of w and then I want to do some job as per the
>> o/p of w command in my linux system. So i have written the code as follows
>>
>> use strict;
>> use warnings;
>>
>> open (LS, "w|") or die "can't open w: $!";
>> my @arr = <LS>;
>> close (LS);
>> shift @arr;
>> shift @arr;
>> my($one,$two,$three,$four,$five,$six,$seven,$eight);
>>
>> foreach my $el(@arr)
>> {
>> ($one,$two,$three,$four,$five,$six,$seven,$eight) = split(/ /,$el);
>> print $five."\n";
>> }
>> but the problem is as per the o/p of w command I want to extract the fifth
>> field but by using the above code I am not able to do this. The o/p of who
>> command in my system is as follows
>>
>> USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
>> bighosh pts/1 bighosh.in.conne 13:48 38:03 0.16s 0.06s sshd:
>> bighosh [priv]
>> nchatter pts/2 nchatterjee.in.c 10:31 15:38 0.68s 0.65s -bash
>> anadhika pts/3 anadhikary.in.co 15:10 0.00s 0.04s 0.00s w
>> suray pts/4 suray1.in.connec 12:36 46:43 0.04s 0.04s -bash
>> merge pts/5 sasarkar.in.conn 12:00 5:44 0.11s 0.11s -bash
>> dpghosh pts/6 dpghosh.in.conne 12:09 1:32 0.07s 0.01s sshd:
>> dpghosh [priv]
>> anadhika pts/7 anadhikary.in.co 13:50 10.00s 0.12s 0.12s -bash
>>
>> I need to extract the idle column. But using my code I am getting output
>> like this
>>
>>
>> pts/4
>> pts/5
>>
>> Where I am making the mistake............ please rectify.....
>>
>> Thanks & Regards in advance
>> Anirban Adhikary
>
> Anirban,
>
> The output of 'w' is delimited by whitespace, not necessarily a single space.
> Try passing the pattern '\w+' to split. Something like this:
I think you mean /\s+/.
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> open (LS, "w|") or die "can't open w: $!";
>
> <LS>;
> <LS>;
>
> while (<LS>) {
> print ((split)[4], "\n");
> }
split with no parameters defaults to a separator pattern of ' ', i.e. a literal
space, which is a special case. It has the same effect as splitting on /\s+/ but
also discards any empty leading field in the case where the object string starts
with whitespace, and is exactly what is wanted here.
Rob
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