Hi, On Friday, December 30, 2011 at 9:00 PM, ankush grover wrote: > Hi Friends, > > I am trying to write a shell script which can merge the 2 columns into > 3rd one on Centos 5. The file is very long around 31200 rows having > around 1370 unique groups and around 12000 unique user-names. > The 1st column is the groupname and then 2nd column is the user-name. I’m not sure I understood that “2 columns into 3rd one” there but... > 1st Column (Groupname) 2nd Column (username) > admin ankush > admin amit > powerusers dinesh > powerusers jitendra If that’s the format of your input and … > The desired output should be like this > > admin: ankush, amit > powerusers: dinesh, jitendra > If that’s your desired output, and assuming the input file is already sorted, try the ff: # -- code starts here --> #!/bin/bash GROUPNAMENOW='' while read LINE do GROUPNAME=$(echo $LINE | cut -d ' ' -f 1) USERNAME=$(echo $LINE | cut -d ' ' -f 2) if [ "$GROUPNAME" == "$GROUPNAMENOW" ]; then echo ", $USERNAME" else GROUPNAMENOW=$GROUPNAME echo -n "$GROUPNAMENOW: $USERNAME" fi done < input.txt # <-- code ends here -- Note: Tested and worked as expected in OS X. It should work in CentOS too. HTH, -- - Edo - mailto:ml2edwin@xxxxxxxxx “Happy are those conscious of their spiritual need …” —Matthew 5:3 _______________________________________________ CentOS mailing list CentOS@xxxxxxxxxx http://lists.centos.org/mailman/listinfo/centos