-l:
1. "chomps" the input (which here means: removes newlines (if present) from each line, more general explanation:
http://perldoc.perl.org/functions/chomp.html
2. and automatically adds a newline to each output newline (see below how to achieve this in a shorter way with a relatively new Perl feature).
-a: turns on auto-split-mode: this splits the input (like awk) into the @F (for fields) array. The default separator is one (or many) spaces, i.e. it behaves like AWK.
-n: makes Perl process the input in an implicit while loop around the input, which is processed line-wise: "as long as there is another line, process it!"
-e: execute the next command line argument as a Perl program (argument in this case beeing 'print $F[0]').
Note that the example can be shortened if you use
-E instead of -e. -E enables all extensions and new features of Perl (which aren't enabled with -e because of backwards compatibility). This allows you to use 'say' instead of 'print' which adds a trailing newline automatically and lets you drop the -l option (if you don't need the 'chomp' behaviour explained above):
$ perl -anE 'say $F[0]'
Of course, the AWK command line is still shorter - and that's expected, because AWK is more specialized than Perl.
Still, Perl one liners are often very useful and can do other things better / shorter than AWK - especially if the one-liner uses one of the many libraries that are available for Perl.
A thorough reference of all Perl command line options is available at:
Thank you, that tempts me to go and look at perl. At the moment I tend to use simple awk, or a full python script. I find python really doesn't lend itself to "one line", or even particularly short, programs however. I keep meaning to go back and look at perl. I was tempted to wait for Perl 6, but I think the time has come to just look at Perl 5 :)
If you're genuinely curious about -lane, my favorite site for Perl one liners has gone the way of all flesh, but the Wayback Machine can still get you a copy[1].
