Hi could you be a bit more specific?

I have tried to use the mktemp command with no joy.

The code I have for doing the job is:

sort $1 > tempfile1.txt
sort $2 > tempfile2.txt
sort $3 > tempfile3.txt

tail -n 1 tempfile1.txt > tempfile4.txt
tail -n 1 tempfile2.txt > tempfile5.txt
tail -n 1 tempfile3.txt > tempfile6.txt

sort -m tempfile4.txt tempfile5.txt tempfile6.txt > tempfile7.txt

sort -r tempfile7.txt > output.txt

Thanks.