This works with the data you provided: 

#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;

my $re = qr{
    user=
    [<"]?
    ( \S+? )
    [>"]?
    ,?
    \s
}x;

while (<DATA>) {
    /$re/;
    say $1;
}

__DATA__
.... user=jtkirk, ip=[::ffff:127.0.0.1], top=0,....
.... user=<jtkirk@enterprise.com>, ip=[::ffff:127.0.0.1], top=0,....
.... user="jtkirk@enterprise.com" passwd="XXXXXX"....

[download]

Output:

$ pm_log_uname_regex.pl
jtkirk
jtkirk@enterprise.com
jtkirk@enterprise.com

[download]

-- Ken

In reply to Re: Getting my username from log by kcott
in thread Getting my username from log by stevbutt

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