Hello,

I assume, you want single matched lines and not blocks of matched lines. Then you could use something like this: 

use strict;
use warnings;

while (defined(my $line = <DATA>)) {
    if ($line =~ m{
        \A N \d+ G \d+ X \d+ \.? \d* Y \d+ \.? \d* K \d+ \.? \d* J \d+
+ \.? \d* H 1 M 25 \n \z
        |
        \A N \d+ M 20 \n \z
        |
        \A N \d+ G 45 \n \z
        |
        \A N \d+ G 01X \d+ \.? \d* Y \d+ \.? \d*  C \d+ \.? \d* M 25 \
+n \z
        }xms) {
        print $line;
    }
}

__DATA__
N335G03X247.16Y580.07K6.89J96.62H1M25
N340M20
N345G45
N350G01X832.56Y692.92C275.44M25
N355M20
N360G46C0
N365G03Y720.88I146.74J13.98H36M25

[download]
which yields 
N335G03X247.16Y580.07K6.89J96.62H1M25
N340M20
N345G45
N350G01X832.56Y692.92C275.44M25
N355M20

[download]
Update: added end-of-line anchors in regular expressions.

In reply to Re: Using regular expressions to find patterns in machine tool data by hexcoder
in thread Using regular expressions to find patterns in machine tool data by merrymonk

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