UNIX Command Line

Input file:

$ cat file1
11
12
13
14

Output required: Print the combination of above lines so that output looks like:

11,12
11,13
11,14
12,11
12,13
12,14
13,11
13,12
13,14
14,11
14,12
14,13

Awk solution:

$ awk '
{ a[$0] }
END {
       for (i in a){
               for (j in a){
                       if (i != j)  print (i "," j)
               }
       }
}' file1

.