Tip #62   Sum numbers from a file, stdin, etc.

Throw this in your command pipeline:

perl -ne '$sum += $_;}{ print "Sum: $sum\n";'

The

}{

closes the

while ( <> ) {

loop that Perl wraps your code in (because of the

-n

) and opens a new one that will only execute after the while loop has finished. You can use this in lots of Perl one-liner tricks.

For a contrived example, to sum the sizes of files in the current directory (learn the joys of cut(1) first):

ls -l | cut -c 30-42 | perl -ne '$sum += $_;}{ print "Sum: $sum\n";'

cut grabs characters 30-42 from stdin, which happen to coincide with my file size column in ls.