How can I print only certain fields in a space separated file? - perl

Question

I have a file containing the following content 1000 line in the following format:
abc def ghi gkl
How can I write a Perl script to print only the first and the third fields?
abc ghi

Answer 1

perl -lane 'print "#F[0,2]"' file

Answer 2

If no answer is good for you yet, I'll try to get the bounty ;-)
#!/usr/bin/perl
# Lines beginning with a hash (#) denote optional comments,
# except the first line, which is required,
# see http://en.wikipedia.org/wiki/Shebang_(Unix)
use strict; # http://perldoc.perl.org/strict.html
use warnings; # http://perldoc.perl.org/warnings.html
# http://perldoc.perl.org/perlsyn.html#Compound-Statements
# http://perldoc.perl.org/functions/defined.html
# http://perldoc.perl.org/functions/my.html
# http://perldoc.perl.org/perldata.html
# http://perldoc.perl.org/perlop.html#I%2fO-Operators
while (defined(my $line = <>)) {
# http://perldoc.perl.org/functions/split.html
my #chunks = split ' ', $line;
# http://perldoc.perl.org/functions/print.html
# http://perldoc.perl.org/perlop.html#Quote-Like-Operators
print "$chunks[0] $chunks[2]\n";
}
To run this script, given that its name is script.pl, invoke it as
perl script.pl FILE
where FILE is the file that you want to parse. See also http://perldoc.perl.org/perlrun.html. Good luck! ;-)

Answer 3

That's really kind of a waste for something as powerful as perl, since you can do the same thing in one trivial line of awk.
awk '{ print $1 $3 }'

Answer 4

while ( <> ) {
my #fields = split;
print "#fields[0,2]\n";
}
and just for variety, on Windows:
C:\Temp> perl -pale "$_=qq{#F[0,2]}"
and on Unix
$ perl -pale '$_="#F[0,2]"'

Answer 5

As perl one-liner:
perl -ane 'print "#F[0,2]\n"' file
Or as executable script:
#!/usr/bin/perl
use strict;
use warnings;
open my $fh, '<', 'file' or die "Can't open file: $!\n";
while (<$fh>) {
my #fields = split;
print "#fields[0,2]\n";
}
Execute the script like this:
perl script.pl
or
chmod 755 script.pl
./script.pl

Answer 6

I'm sure I shouldn't get the bounty since the question asks for the result to be given in perl, but anyway:
In bash/ksh/ash/etc:
cut -d " " -f 1,3 "file"
In Windows/DOS:
for /f "tokens=1-4 delims= " %i in (file) do (echo %i %k)
Advantages: like others said, no need to learn Pearl, Awk, nothing, just knowing some tools. The result of both calls can be saved to the disk by using the ">" and the ">>" operator.

Answer 7

while(<>){
chomp;
#s = split ;
print "$s[0] $s[2]\n";
}
please start to go through the documentation as well

Answer 8

#!/usr/bin/env perl
open my$F, "<", "file" or die;
print join(" ",(split)[0,2])."\n" while(<$F>);
close $F

Answer 9

One easy way is:
(split)[0,2]
Example:
$_ = 'abc def ghi gkl';
print( (split)[0,2] , "\n");
print( join(" ", (split)[0,2] ),"\n");
Command line:
perl -e '$_="abc def ghi gkl";print(join(" ",(split)[0,2]),"\n")'