in reply to How does $. work in one liner?

In your example, you don't need the $_. This will print lines 1 and 2 from the file test.txt: 

perl -ne 'print if 1..2' test.txt

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If you prefer to be more explicit: 
perl -ne 'print if $. >= 1 && $. <= 2' test.txt

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This type of question comes up often enough that I keep a list of one-liner references.

Update: See also:

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Re^2: How does $. work in one liner?
by afoken (Chancellor) on May 29, 2016 at 08:51 UTC
    In your example, you don't need the $_. This will print lines 1 and 2 from the file test.txt:

    Assuming an OS that follows the POSIX spirit, this will also print the first two lines of a file, but probably without reading the entire file, and probably without starting an interpreter:

    head -n 2 test.txt

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    (POSIX: head)

    Alexander

    --
    Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)
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