Regarding your update, where you show a modified version of the code I suggested, I should point out a minor (harmless) misconception in your final "for" loop to print the results. Here's your version of the for loop: 
for (sort keys %data) {
    my @content = "$data{$_},$_";
    if (grep(/.*,.*,.*,.*$/, @content)){
        @column = grep(/.*,.*,.*,.*$/, @content)
    };
    #@column = grep(/.*,.*,.*,.*$/, @content);
    print $fh_out "@column\n"; 
}

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The second line assigns a single string to an array (@content). This is bad form, but perl will "do the right thing" and create the array with a single element, which is the string you supplied: "$data{$_},$_" .

Next, the "if" condition returns true if the single array element happens to match your regex, where you appear to be testing whether a string contains at least three commas. If it matches, you use grep on the single element in @content to store the string in a new array "@column". (Looks like you have removed "use strict;" because @column appears to be working as an undeclared global -- bad idea.) Anyway, if the match fails, @column remains undefined. UPDATE: rather, @column remains unchanged -- it still holds whatever may have been assigned to it previously, if anything. That could cause a problem in your output.

Regardless of what happens with that if condition, you print @column followed by a line-feed (even if it's undefined --update: or contains a string from a previous iteration).

All of that would be better stated as follows: 

for ( sort keys %data ) {
    print "$data{$_},$_\n" if ( $data{$_} =~ /,.*?,/ );
}

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(that is, if the original value of "$data{$_}" contains two commas, add ",$_\n" at the end and print it; otherwise skip it)

In reply to Re: Joining two files on common field by graff
in thread Joining two files on common field by ch1

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