Question

I have a file that looks like this:

dee    123    
bee    555    
dee    56    
cee    29    
dee    30    
cee     13

I need the output like this:

dee  123,56,30    
bee  555    
cee   29,13

How can I perform this task using perl one-liners?

Answer 1

perl -alnwe '
    push @{$a{$F[0]}}, $F[1]; 
    }{ 
    for (keys %a) { print $_, "  ", join ",",@{$a{$_}} } ;'

Output:

cee  29,13
dee  123,56,30
bee  555

Explanation:

• -a autosplit input line on whitespace
• -l handle newlines
• -n assume while(<>) loop around program
• @F array comes from autosplit, $F[0] and $F[1] are the array elements.
• %a is where we store results, first column as keys, second in the value as an array
• }{ the eskimo operator, with the -n switch does the same as an END block

In the last section we just print the keys and values.