Shell Programming and Scripting

{
  arr[$1] = ($1 in arr) ? arr[$1] "," $2 : $2
}
END {
  for (i in arr)
    print i, arr[i]
}

#!/usr/bin/env python
                                                                                                          
import sys
                                                                                                          
groups={}
                                                                                                          
while 1:
     line = sys.stdin.readline()
     if line == '':
         break
     try:
         key,value=line.strip().split()
         if not groups.has_key(key):
            groups[key]=[value]
         else:
            groups[key].append(value)
     except:
         pass
                                                                                                          
keys=groups.keys()
keys.sort()
for key in keys:
    print key,
    print ",".join(groups[key])