...or more legibly

I think you might be obscuring the wood with a lot of trees there! Perhaps use of the -n switch would be applicable here, either in a script or as a one-liner.

$ cat rubbish
Line1
Line2
Line3
Line4
Line5
Line6
Line7
Line8
Line9
Line10
Line11
Line12

$ perl -ne 'print if 2 .. 7;' rubbish 
Line2
Line3
Line4
Line5
Line6
Line7
$

[download]

The array slice method is, as you say, only suitable for small files whereas using -n when combined with last is more efficient when interested only in lines at the beginning of large files. The following examples were acting on a 2,000,000+ line log file.

# time perl -ne 'print if 5 .. 10' maillog
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...

real    0m1.206s
user    0m0.773s
sys     0m0.432s
# time perl -ne 'print if 5 .. 10; last if $. > 10' maillog
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...
Nov 11 04:19:28 ...

real    0m0.013s
user    0m0.006s
sys     0m0.008s
#

[download]

I hope this is of interest.

Cheers,

JohnGG

In reply to Re^3: regex issue by johngg
in thread regex issue by pinnacle

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