[SOLVED] Are regular expressions work correct in Slackware 14.2 and current? Cacti problem

Olek · 12-04-2016, 02:10 PM

After upgrade from Slack 14.1 to 14.2 my Cacti stopped to show load average.
It's because perl script loadavg.pl, which before produced correct data, now put one stupid comma in output. I don't now why?

Should be

Code:

0.20 0.15 0.14

but script output is

Code:

0.20 0.15, 0.14

Cacti don't like this comma and says:

Code:

Result from CMD not valid.  Partial Result: 0.20 0.15, 0.14

Can You check script below on Yours systems?
And how to fix it?

My loadavg.pl (in original script there isn't "LC_ALL=C" but without it I get more commas)

Code:

#!/usr/bin/perl

#get load avg for 5;15;30 min
#
open(PROCESS,"env LC_ALL=C uptime |");
$avg = <PROCESS>;
$avg =~ s/.*:\s*//;
close(PROCESS);

if ($ARGV[0] eq "5") {
        $avg = `echo "$avg" | awk '\{print \$1 \}'`;
}

if ($ARGV[0] eq "15") {
        $avg = `echo "$avg" | awk '\{print \$2 \}'`;
}

if ($ARGV[0] eq "30") {
        $avg = `echo "$avg" | awk '\{print \$3 \}'`;
}

chomp $avg;
$avg =~ s/,//;
$avg =~ s/\n//;
print $avg;

Turbocapitalist · 12-04-2016, 02:16 PM

See man perlre for the details on regular expressions and the s/// substitution operator, and man perlop as well. What you need is a "g" in the third to last line.

Also, "perl" is far more powerful than "awk" so you can safely replace the calls to "awk" with native perl.

kjhambrick · 12-04-2016, 03:17 PM

Olek --

As far as I know, uptime has always produced output like this:

Code:

 15:10:47 up 2 days,  9:03, 23 users,  load average: 0.16, 0.15, 0.16

man uptime ?

What is it you need to 'feed' Cacti ?

-- kjh

Code:

#
# Slackware 13.37:
#
[konrad@kjhlt5 ~]$ uptime
 15:11:37 up 9 days,  8:56,  2 users,  load average: 0.12, 0.10, 0.13
#
# Slackware 14.2:
#
[konrad@kjhlt6 ~]$ uptime
 15:11:52 up 2 days,  9:04, 23 users,  load average: 0.11, 0.13, 0.15
#
# CentOS 6.x
#
[konrad@broke ~]$ uptime
 15:14:08 up 9 days, 19:23,  1 user,  load average: 0.02, 0.02, 0.00
#
# CentOS 5.x
#
[konrad@pp310 ~]$ uptime
 15:13:22 up 237 days, 23:52, 14 users,  load average: 0.33, 0.15, 0.19
#
# CentOS 4.x
#
[konrad@sog ~]$ uptime
 15:14:54 up 18 days,  1:12,  1 user,  load average: 0.03, 0.09, 0.04

allend · 12-04-2016, 03:32 PM

Quote:

Also, "perl" is far more powerful than "awk" so you can safely replace the calls to "awk" with native perl.

Personally, I would drop the "perl", as "awk" can cope.

Code:

#!/bin/sh

(( $1 == 5 )) && uptime | awk '{print gensub(",","","g",$(NF-2))}'
(( $1 == 15 )) && uptime | awk '{print gensub(",","","g",$(NF-1))}'
(( $1 == 30 )) && uptime | awk '{print $NF}'

kjhambrick · 12-04-2016, 03:57 PM

Thanks allend

I am an `awk guy` myself unless I need to handle binary data

This would also work and I believe it handles the case where not( $1 in 5,15,30 ) the same as Olek's script ( it dumps all-three times ).

Once again though, uptime returns load average for 1, 5 and 15 min and not 5, 15 and 30 min ...

Try man uptime

EDIT: oops ... I meant to say that Turbocapitalist is correct, Olek's substitution needs a trailing 'g' for global: $avg =~ s/,//g;

-- kjh

Code:

#!/bin/sh

uptime |\
gawk '
BEGIN {

   Arg = "'"$1"'"  +0

   OFS = FS = " "

   getline

   gsub( /,/, "", $0 )

   if ( Arg == 5 )
   {
      print $(NF-2)
      exit( 0 )
   }
   if ( Arg == 15 )
   {
      print $(NF-1)
      exit( 0 )
   }
   if ( Arg == 30 )
   {
      print $(NF)
      exit( 0 )
   }
   print $(NF-2),$(NF-1),$(NF)
   exit( 1 )
}'

Olek · 12-04-2016, 04:12 PM

Thank You for help. I try to study man perl, but a don't now Perl at all.
Or maybe I'll use this perlless script

And please note:
1. The "loadavg.pl" script was delivered by Cacti package from SBo, so now will make problems not only for me, I thing.
2. This script work fine on Slackware 14.1 so what changed in Slackware 14.2 ?

Olek

kjhambrick · 12-04-2016, 04:43 PM

Thanks for the info Olek.

I build the cacti Package from SBo and I found: var/www/htdocs/cacti/scripts/loadavg.pl in the resulting Package.

The Code provided by the Cacti Devs in loadavg.pl is broken.

I am not sure why that same script worked on Slackware 14.1 ... there was a major perl update but as Turbocapitalist said, $avg =~ s/,//; will only remove the first comma ( it has been that way since perl 4 ).

In addition, your LC_ALL=C patch is probably REQUIRED these days because some LOCALES use commas instead of dots for the decimal char.

The LC_ALL=C Environment will assure that the decimals are dots.

I would say that the Cacti Devs need to patch their loadavg.pl script.

Being a coder myself, I am hesitant to criticize code written by other coders but here goes ...

As Turbocapitalist said, there is no need to invoke gawk inside a perl script.

As allend said the same thing can be done without perl at all.

IMO, the loadavg.pl script is VERY primative in that it invokes gawk with back-ticks in a perl script to do something that perl capable of doing very well all by itself ( what Turbocapitalist said ).

While that particular script shouldn't be dangerous security-wise, it is however VERY poorly designed (

Larry Wall might have a Camel if he saw it

)

I am not sure what other plugins are provided by the Cacti Devs, but given what I see in loadavg.pl, I would tend to be careful deploying their stuff on internet-facing web servers without auditing their code.

Anyhow, my $0.02 ...

-- kjh

kjhambrick · 12-04-2016, 05:12 PM

On more Olek ...

Since this is a plugin for a php app, you may need a pure-d perl script ( except that the perl script invokes uptime via popen() ).

Below is one that doesn't use gawk but it does invoke uptime via backticks instead of opening a pipe.

There are probably better ways to do it but this one does do what you were looking for in your first post.

HTH.

-- kjh

Code:

#!/usr/bin/perl
# 
# get load avg for 5;15;30 min
#
my $avg = `LC_ALL=C uptime` ;

chomp( $avg ) ;

$avg =~ s/,//g ;

my @fields = split( / /, $avg ) ;

if ( $ARGV[0] eq "5" )
{
   print $fields[ $#fields -2 ] . "\n" ;
}
elsif ( $ARGV[0] eq "15" )
{
   print $fields[ $#fields -1 ] . "\n" ;
}
elsif ($ARGV[0] eq "30" )
{
   print $fields[ $#fields ] . "\n" ;
}
else
{
   print $fields[ $#fields -2 ] 
       . ' ' 
       . $fields[ $#fields -1 ] 
       . ' ' 
       . $fields[ $#fields ] 
       . "\n" ;
}
exit( 0 );

GazL · 12-05-2016, 04:29 AM

You can save yourself a lot of trouble by just reading the data from /proc/loadavg rather than trying to capture/parse the output of uptime.

GazL · 12-05-2016, 04:29 AM

You can save yourself a lot of trouble by just reading the data from /proc/loadavg rather than trying to capture/parse the output of uptime.

edit: oops, duplicate post. No idea how that happened.

kjhambrick · 12-05-2016, 05:41 AM

Interesting idea GazL.

Especially if the output of the `uptime` is a non-portable.

Same load numbers on this run ( and there are no commas

)

Code:

# cat /proc/loadavg ; uptime

0.24 0.18 0.12 1/618 17927
 05:29:22 up 2 days, 23:22, 23 users,  load average: 0.15, 0.14, 0.10

OTOH, if uptime is portable across 'NIX OS then I imagine the Cacti guys would opt for the portable approach.

Out of curiosity, I did dig around a bit in the Cacti var/www/htdocs/cacti/scripts/ directory.

There are {.sh,.pl,.php} command line scripts in there.

In addition, there is one script: var/www/htdocs/cacti/scripts/loadavg_multi.pl that is more 'perlish' than loadavg.pl

Code:

#!/usr/bin/perl

#get load avg for 1;5;10 min
open(PROCESS, "uptime |");
$avg = <PROCESS>;
close(PROCESS);

#   9:36pm  up 15 days, 11:37,  2 users,  load average: 0.14, 0.13, 0.10

$avg =~ s/^.*:\s(\d+\.\d{2}),?\s(\d+\.\d{2}),?\s(\d+\.\d{2})$//;

print "1min:$1 5min:$2 10min:$3";

The output is different than loadavg.pl but it is a pure-d perl script ( no `gawk` backtick commands ) and the $avg =~ RegEX accounts for optional commas between the 1,5,15 load avg numbers.

Anyhow ... Thanks again.

-- kjh

Olek · 12-10-2016, 04:37 PM

Finally i found that now, with cacti-0.8.8h the only way is to use loadavg_multi.pl script.
It's funny that on Slackware 14.1 with cacti-0.8.81_p1 loadavg.pl script worked fine.
Now, on clean new install of Cacti loadavg_multi.pl script is used by default.
All because I upgraded my system instead of building everything from scratch

I guess so current Cacti not accept output of loadavg.pl script any more.

Thanks for Your help.

Olek

kjhambrick · 12-11-2016, 02:04 PM

Thanks for the update Olek.

One thing you might do for posterity is to mark your Thread as SOLVED.

As the O.P. Only you can do that.

And should someone else have the same issue, that SOLVED Tag is good to add to your LQ Searches.

Thanks again.

-- kjh

Olek · 12-12-2016, 02:51 AM

Quote:

Originally Posted by kjhambrick

One thing you might do for posterity is to mark your Thread as SOLVED.

But I alredy marked thread as SOLVED.
Isn't its status visible?

Olek

kjhambrick · 12-12-2016, 02:37 PM

I missed it before but I see it now, Olek

Thanks and sorry about causing confusion.

-- kjh