Hi RenMcCourtey,

Is this what you're looking for?

$ cat in.txt 
AaX
ObU
UcU
XdR
ZeZ
UfH
UgU
FhA
OiG
UjX
UkZ
UlZ
xmT
$ perl -pe 'chomp if /^U/' in.txt 
AaX
ObU
UcUXdR
ZeZ
UfHUgUFhA
OiG
UjXUkZUlZxmT
[download]

Update: Explanation: When using the -p switch without the -l switch (perlrun), each line read into $_ still contains the newline, which is normally output when the lines are printed back out. So the chomp just chops the newline off, and those lines are printed without the final newline.

Hope this helps,
-- Hauke D