Re^2: Regex: negative look ahead

Hi there I am writing a script with tails a log file and for each line runs multiple regular expressions against it (which are contained in a config file). Below are some examples of the log lines

ERROR 2012-04-02 05:00:18 Error processing Cancel Execution '2012-CSNY
+1CMR-1-20120402-1247 52938803o122h090000507' with LHDRSeqId 'CSNY1CMR
+1-1333315812780-2759'.

[2012-04-02 07:04:27,275][ERROR][101574:Company:japan][analytics.bond.
+BondAlibImpl] ALIB license will expire in29 days. Please upgrade lice
+nse file under /app/license

2012-04-02 05:00:18,810[ERROR] limitCheck: error while checking instru
+ction xxx.core.biz.order.instruction.EquityOrderSubmitInstruction(tsI
+d=20120402-090237887-340-509,order=20120402-090237880-767-508:TS)
[download]

With my original regular expression I would want to ignore the first two lines but match the third line. Thanks!

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Re^3: Regex: negative look ahead by brx (Pilgrim) on Apr 10, 2012 at 14:37 UTC
It could be a good idea to split the big regex. A good example: if you want to match lines with the words 'red' and 'dog'. The first idea is often to write something like: `$line =~ /red.dog\|dog.red/` but there is a better way: `$line=~/dog/ and $line=~/red/` So, it's probably better to treat each exclusion with one regex: `next if /regex/;` while (my $line = <DATA>) { next if $line =~ /^ERROR.?Error processing Cancel Execution/; next if $line =~ /ERROR.?license will expire/; print "Do something with the line: $line"; } __DATA__ ERROR 2012-04-02 05:00:18 Error processing Cancel Execution '2012-CSNY +1CMR-1-20120402-1247 52938803o122h090000507' with LHDRSeqId 'CSNY1CMR +1-1333315812780-2759'. [2012-04-02 07:04:27,275][ERROR][101574:Company:japan][analytics.bond. +BondAlibImpl] ALIB license will expire in29 days. Please upgrade lice +nse file under /app/license 2012-04-02 05:00:18,810[ERROR] limitCheck: error while checking instru +ction xxx.core.biz.order.instruction.EquityOrderSubmitInstruction(tsI +d=20120402-090237887-340-509,order=20120402-090237880-767-508:TS) [download]	[reply] [d/l] [select]

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Re^3: Regex: negative look ahead
by brx (Pilgrim) on Apr 10, 2012 at 14:37 UTC

It could be a good idea to split the big regex.

A good example: if you want to match lines with the words 'red' and 'dog'.

The first idea is often to write something like: $line =~ /red.*dog|dog.*red/

but there is a better way: $line=~/dog/ and $line=~/red/

So, it's probably better to treat each exclusion with one regex: next if /regex/;

while (my $line = <DATA>) {
    next if $line =~ /^ERROR.*?Error processing Cancel Execution/;
    next if $line =~ /ERROR.*?license will expire/;
    print "Do something with the line: $line";
}
__DATA__
ERROR 2012-04-02 05:00:18 Error processing Cancel Execution '2012-CSNY
+1CMR-1-20120402-1247 52938803o122h090000507' with LHDRSeqId 'CSNY1CMR
+1-1333315812780-2759'.
[2012-04-02 07:04:27,275][ERROR][101574:Company:japan][analytics.bond.
+BondAlibImpl] ALIB license will expire in29 days. Please upgrade lice
+nse file under /app/license
2012-04-02 05:00:18,810[ERROR] limitCheck: error while checking instru
+ction xxx.core.biz.order.instruction.EquityOrderSubmitInstruction(tsI
+d=20120402-090237887-340-509,order=20120402-090237880-767-508:TS)
[download]

[reply]
[d/l]
[select]