extract multiples columns from txt file perl

Question

I have a txt file like this:

#Genera columnA columnB columnC columnD columnN
x1       1       3       7      0.9      2
x2       5       3       13     7            


        

Answer 1

There are command line switches that are used for this kind of application:

perl -lnae 'print join "\t", @F[1,3,5]' file.txt

Switch -a automatically creates variable @F for each line, split by whitespace. So @F[1,3,5] is an array slice of elements 1, 3, and 5.

The downside of this, of course, is that you have to use the column numbers instead of the names.