TMTOWTDI: I like to think of awk as baby perl - a really fast baby. 
awk '{
  seen[$1] = $2","seen[$1] ;
}
END {
  for (key in seen) {
    print key" "seen[key] ;
  }
}
' /your/file.txt > /your/newfile.txt

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In reply to Re^3: Perl hashes: is there some way of adding more data to the value associated with an existing key? by onelesd
in thread Perl hashes: is there some way of adding more data to the value associated with an existing key? by mertserger

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