I could format the data using a perl script (hash). I am wondering if it can be done through some shell one liner, so that every time I dont need to write a perl script if there is some change in the  

input format.
Example Input:

```
rinku   a
rinku   b
rinku   c
rrs     d
rrs     e
abc     f
abc     g
abc     h
abc     i
xyz     j

```

example Output:

```
rinku  a,b,c
rrs    d,e
abc    f,g,h,i
xyz    j

```

Please help me with a command using shell/awk/sed to format the input.

Thanks,
Rinku