Hello littlewenwen, and welcome to the Monastery!
Yes, you can do in-line updates using the standard Tie::File module:
#! perl
use strict;
use warnings;
use Tie::File;
my $filename = 'RawFile.txt';
tie my @lines, 'Tie::File', $filename or die "Cannot tie file '$filena
+me': $!";
for my $i (0 .. $#lines)
{
my @fields = split /\t/, $lines[$i], -1;
@fields = map { $_ eq '' ? 'Missing' : $_ } @fields;
$lines[$i] = join("\t", @fields);
}
untie @lines;
Output in RawFile.txt:
abcd 123 456 defg
cdefg 23 Missing as
Missing 345 235 Missing
xsd Missing swe Missing
Hope that helps,
Update 1: Added -1 as LIMIT argument to split to get trailing empty fields.
Update 2: Added final “Missing” to output; the final tab was missing from my input file on line 4. Thanks to kcott for the heads-up.
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