Trying to grab process output.

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I just wrote something with awk which fetches my unix ps -ef output where I eliminate the awk and /bin/ksh part of the script that is fetching my ps -ef output:

jones 11111 33334 09:37:46 awk
jones 11113 44454 09:37:46 grep
jones 11123 33334 09:37:46 /bin/ksh
jones 11118 22234 06:18:58 -ksh
[download]

to this

jones   11135 44322 09:39:38 grep
jones   11118 22234 06:18:58 -ksh
[download]

Here is how I did it with Unix:

ps -ef | grep Jones | awk '$8 !~ /awk/ && $8 !~ /\/bin\/ksh/ \
{print $1" "$2" "$3" "$5" "$8}'
[download]

Now my attempt to do it with perl shows this in my output file:

jones 11111 55555 0 09:42:09 pts/1    0:00 /usr/local/bin/perl ps1
jones 22222 66666  0 09:42:09 pts/1    0:00 grep jones
jones 33333 77777  0 09:42:09 pts/1    0:00 sh -c ps -ef | grep jones 
+> out
r
jones 44444 88888  0 06:18:58 pts/1    0:01 -ksh
[download]

I want this output (the same as I got in my unix script):

jones 22222 66666  0 09:42:09 pts/1    0:00 grep jones
jones 44444 88888  0 06:18:58 pts/1    0:01 -ksh
[download]

Here is my attempt at it in Perl. Please advise how I can improve this so it works???

#!/usr/local/bin/perl
system("ps -ef | grep Jones > outr");
$outr = 'outr';
open(OF, "$outr") || die "Can not open $outr: $!\n";
@data=(<OF>);
close(OF);
open(OF,">$outr") || die "File not opening $outr: $!\n";

foreach $_ (@data)
{
next if ($_ !~ m/\/usr/local/bin/perl ps1$/) && ($_ !~ /sh \-c ps \-ef
+ \| grep jones \> out) ;
print OF $_;
}
close(OF);
[download]

Comment on Trying to grab process output. Select or Download Code

Replies are listed 'Best First'.
Re: Trying to grab process output. by rob_au (Abbot) on Jul 16, 2002 at 14:10 UTC
I would recommend that you have a look at Proc::ProcessTable - It provides a very easy and neat interface to the `/proc` filesystem for the delivery of this information (as opposed to parsing the output of `ps`). There is a review of this module on this site with examples of usage from myself here and here.	[reply] [d/l] [select]
Re: Trying to grab process output. by Abigail-II (Bishop) on Jul 16, 2002 at 14:10 UTC
`open my $fh, "ps -ef \| grep Jones \|" or die; while (<$fh>) { my @F = split; next if $F [7] =~ /perl/ \|\| $F [7] =~ /ps -ef/ \|\| $F [7] =~ m{/bin/ksh}; print "@F[0,1,3,4,7]\n"; }` [download] Abigail	[reply] [d/l]
Re: Re: Trying to grab process output. by Anonymous Monk on Jul 16, 2002 at 19:23 UTC
Thanks to all.	[reply]
Re: Trying to grab process output. by cybear (Monk) on Jul 16, 2002 at 14:11 UTC
Some suggestions: Don't use "system" use back-ticks ``. Like this: my $outr = `ps -ef\|grep Jones\|grep -v awk\|grep -v ksh`; That will assign the output of your ps to $outr. Or: my $outr = `ps -ef\|grep Jones`; @outr = split(/\n/, $outr); foreach (@outr) { unless (($_ eq /bin/ksh) or ($_ eq awk)) { print "$_\n"; } } [download] I think that one of these will do what you want. And if you don't want to use ps -ef there are some modules that will return this kind of system process info also.	[reply] [d/l] [select]
Re: Trying to grab process output. by thelenm (Vicar) on Jul 16, 2002 at 14:26 UTC
The code you provided seems to have a few syntax errors (e.g., `/usr/local/bin/perl` needs the slashes to be escaped, and the regex beginning with `sh` is never terminated), but I've tried to clean it up as well as I could. This program is not equivalent to your Unix grep/awk pipeline, but I've tried to keep the meaning of your Perl code approximately the same. #!/usr/local/bin/perl use strict; use warnings; open(OF,">outr") \|\| die "File not opening outr: $!\n"; foreach (`ps -ef \| grep jones` =~ /[^\n]*\n/g) { next if m!/usr/local/bin/perl ps1$! or /sh -c ps -ef \\| grep jones > + outr$/; print OF; } close(OF); [download] Hopefully this does about what you want. A couple of points about it: Backticks are used to capture the output of `ps` rather than a `system` with output piped to a file. "Jones" is changed to "jones" in the `grep`, since I think that's what you want. The elements of the array in a `foreach` are automatically aliased to `$_`, so there's no need to do it manually. Similarly, `$_` is used by default by regexes and `print`, so there's no need to specify it there, either. -- Mike `-- just,my${.02}`	[reply] [d/l] [select]