Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical

Perl equivlanet of simple awk

by Anonymous Monk
on Mar 19, 2011 at 21:57 UTC ( #894193=perlquestion: print w/replies, xml ) Need Help??
Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

For use in a Perl cgi script, what's an equivalent of the following awk command

awk '/ {print $2}' /home/bob/db.txt

Assume db.txt contains 4 columns, with a valid email address in the first column, and a password in the second column. (For this purpose, security isn't an issue.) I just want to retrieve a password associated with an email address.

Replies are listed 'Best First'.
Re: Perl equivlanet of simple awk
by repellent (Priest) on Mar 19, 2011 at 22:19 UTC
    This equivalent on the command line:
    perl -alne 'print $F[1] if /user\' /home/bob/db.txt

    See Command Switches.

    Expanded code:
    use warnings; use strict; open my $FH, '<', '/home/bob/db.txt' or die $!; while (local $_ = <$FH>) { chomp; print((split ' ')[1], "\n") if /user\; }

    Update: Added expanded code.
Re: Perl equivlanet of simple awk
by wind (Priest) on Mar 19, 2011 at 22:16 UTC
    It's possible to do something like that very easily with a one-liner. However, more verbose is probably what you're looking for if you intend to include this within a script.
    my $file = '/home/bob/db.txt'; open my $fh, $file or die "$file: $!"; my $pass; while (<$fh>) { chomp; my @fields = split /\s+/; if ($fields[0] eq '') { $pass = $fields[1]; last; } } close $fh;
Re: Perl equivlanet of simple awk (a2p)
by LanX (Chancellor) on Mar 20, 2011 at 02:17 UTC
    for such conversions you can use a2p

    > echo '/ {print $2}' |a2p #!/usr/bin/perl eval 'exec /usr/bin/perl -S $0 ${1+"$@"}' if $running_under_some_shell; # this emulates #! processing on NIH machines. # (remove #! line above if indigestible) eval '$'.$1.'$2;' while $ARGV[0] =~ /^([A-Za-z_0-9]+=)(.*)/ && shift; # process any FOO=bar switches $, = ' '; # set output field separator $\ = "\n"; # set output record separator while (<>) { ($Fld1,$Fld2) = split(' ', $_, -1); if (/ { print $Fld2; } }

    anyway you're not checking the first column but the whole line for an email address.

    consider prepending an ^ in your regex.

    Cheers Rolf

    UPDATE: IMHO the @ in the regex should be escaped to avoid array interpolation, seems to be a bug in a2p.

Re: Perl equivlanet of simple awk
by urbansumo (Novice) on Apr 15, 2015 at 11:52 UTC

    Youve just revolutionsied my whole life!! How did I never know about A2p! Thats amazing!

    Thank you so much!

    The Urban Sumo

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: perlquestion [id://894193]
Approved by ww
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others chilling in the Monastery: (5)
As of 2017-03-23 04:37 GMT
Find Nodes?
    Voting Booth?
    Should Pluto Get Its Planethood Back?

    Results (281 votes). Check out past polls.