remove lines that do not match search pattern

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

Folks: Been a while since I posted last, and I require a little pointing in the right direction - I am looking for a very simple solution, which removes lines that 'do not' match my criteria. I have a Expect script which dumps into a few generic devices, and logs out the session; however, I only want a few lines of the output. With the latter in mind - I have tried to fine tune my logging session for Expect; however, for some odd reason I must capture the entire session - otherwise nothing is captured. Due to the latter, I thought this would be a good exercise to learn more perl.

Expect session output = logout.txt

00:eb:99:33:bc:2c    some string of text
00:eb:99:33:bc:2c   Tx        -.34  32423
00:eb:99:33:bc:2c  null
device log entries are empty - log service did not start
98:ab:34:12:ac:3c   Rx  critical
Tx critical   00:eb:99:33:bc:2c
device log entries are full 00:eb:99:33:bc:2c
[download]

The output is not formatted any particular way due to embedded firmware. What I am hoping to do is remove the lines, which do not have a MAC address in them. I am thinking I can do something like 0-1|a-e: 0-1|a-e: 0-1|a-e: 0-1|a-e:~ To match the MAC address format. Looking for direction on how to do this - I have no clue where to start, or what to look for. Thank you JW

Comment on remove lines that do not match search pattern Download Code

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Re: remove lines that do not match search pattern by NetWallah (Canon) on Aug 03, 2015 at 14:24 UTC
From "perldoc perlop": `Binary "!~" is just like "=~" except the return value is negated in th +e logical sense.` [download] So - use your pattern, and negate the match. Try this pattern: `!~/(:?[\da-f]{2}:){5}[\da-f]{2}/` [download] or better, Regexp::Common::net provides built-in regex matching for mac addresses. Clarity: it's like that one thing that is not the other thing, except for when it is.	[reply] [d/l] [select]
Re^2: remove lines that do not match search pattern by jasonwolf (Sexton) on Aug 06, 2015 at 18:00 UTC
Thank you for your suggestions and direction on the regex pattern. I was able to get something working, and the ability to parse through my files.	[reply]
Re: remove lines that do not match search pattern by ww (Archbishop) on Aug 03, 2015 at 14:17 UTC
Capture lines that 'do not' ( `!~` ) match your regex... or capture lines that are not excluded by `unless =~ your regex` Or did you mean you want another way to write the regex (which should be enclosed by code tags for readability). Spirit of the Monastery	[reply] [d/l] [select]
Re^2: remove lines that do not match search pattern by jasonwolf (Sexton) on Aug 03, 2015 at 14:27 UTC
I only want to save the lines that match - meaning that only have a MAC address in the line, and delete all other data. thanks!	[reply]
Re: remove lines that do not match search pattern by pme (Monsignor) on Aug 03, 2015 at 14:12 UTC
Hi jasonwolf, You can do that in your Expect (http://expect.sourceforge.net/) script. Expect is a Tcl extension and Tcl (http://wiki.tcl.tk) has regexp: http://wiki.tcl.tk/986. Do you really need separate script to filter the log?	[reply]
Re^2: remove lines that do not match search pattern by jasonwolf (Sexton) on Aug 03, 2015 at 14:24 UTC
Thanks for the suggestions as to using Expect. I will take a look at this Just for my own knowledge - what do I call what I am trying to do with 0-9\|a-e:0-9\|a-e?	[reply]
Re^3: remove lines that do not match search pattern by AnomalousMonk (Archbishop) on Aug 03, 2015 at 17:04 UTC
... what do I call what I am trying to do with 0-9\|a-e:0-9\|a-e? Assuming you're actually working with `[0-9]\|[a-e]:[0-9]\|[a-e]` (please use `<code> ... </code>` tags in future; please see Writeup Formatting Tips, Markup in the Monastery), it can be explained as: c:\@Work\Perl\monks>perl -wMstrict -le "use YAPE::Regex::Explain; ;; my $rx = qr{ [0-9] \| [a-e]:[0-9] \| [a-e] }xms; print YAPE::Regex::Explain->new($rx)->explain; " The regular expression: (?msx-i: [0-9] \| [a-e]:[0-9] \| [a-e] ) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?msx-i: group, but do not capture (with ^ and $ matching start and end of line) (with . matching \n) (disregarding whitespace and comments) (case-sensitive): ---------------------------------------------------------------------- [0-9] any character of: '0' to '9' ---------------------------------------------------------------------- \| OR ---------------------------------------------------------------------- [a-e] any character of: 'a' to 'e' ---------------------------------------------------------------------- : ':' ---------------------------------------------------------------------- [0-9] any character of: '0' to '9' ---------------------------------------------------------------------- \| OR ---------------------------------------------------------------------- [a-e] any character of: 'a' to 'e' ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- [download] See YAPE::Regex::Explain for regexes of Perl version 5.6 or before. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^3: remove lines that do not match search pattern by pme (Monsignor) on Aug 03, 2015 at 21:08 UTC
OT Filtering with Tcl/expect: `#!/usr/bin/expect while {[gets stdin line] >= 0} { if {[regexp {([[:xdigit:]]{2}:?){6}} $line]} { puts $line } }` [download]	[reply] [d/l]
Re: remove lines that do not match search pattern by Anonymous Monk on Aug 03, 2015 at 15:10 UTC
`grep -v` ...	[reply]
Re: remove lines that do not match search pattern by GotToBTru (Prior) on Aug 04, 2015 at 13:09 UTC
Do you really want to remove lines that don't have a MAC address, or do you want to keep lines that do? I don't have Expect installed, so I can't test this, but looking at the documentation, it appears the $obj->expect($cmd,@params) and $obj->matchlist() contain the functionality you need. @params needs to contain a single entry, a regex that matches MAC addresses. matchlist() will return an array(?) of matching lines from the output of $cmd. Dum Spiro Spero	[reply]