Butterfly in Perl command line "}{"

Saturday, April 26, 2014 perl 0 Comments

I recently came to know about this and I thought its worth sharing. I will try to keep it very simple.
Lets say I have a file as below:

1
2
3
4
5

I need to join all the lines with a pipe so that my output should look like below:

1|2|3|4|5

Normally I use the below command to achieve the same:

perl -lne 'push @a,$_;END{print join "|",@a}' File

Now, here's another option for you below:

perl -lne 'push @a,$_;}{ print join "|",@a' File

The change here is:
}{
This is called butterfly option in perl. Basically it closes while loop imposed by -n switch, and what follows }{ is block executed after while loop.