If it's a green corroded pipe then it's old copper. -You can't fix it. Replace all the length of corroded pipe with PEX and a union at each end
If it is leaking when you use the shower, not shutting off completely, it will need to be replaced. If it is leaking at the wall, take it off and reseal the thread on the pipe with either pipe dope or Teflon tape and reinstall.
More information needed. Is it visible, is it underground, is is plastic, is it metal pipe - -
Demo a section of the wall.
You must break or cut the wall at that point. No other option
Green fluid leaking from a car is radiator fluid. "A professional certified mechanic can handle the repair or maintenance needed to fix this issue."
By calling a licensed master plumber / licensed gas fitter / Gas supplier
If it is galv. pipe there could be a small hole on threads. You would have to replace pipe.
This depends on the size and the location of the leak. It depends because a leak on the straight piece of the pipe will differ from a leak on the joint of the pipe. It also depends on the corrosion of the pipe and the extent as to how bad it is.
If it is leaking from the control, you should be able to access that from the front. If it is the supply lines or the pipe to the shower head, there may be access behind it in a closet. If not, you just have to cut a hole to get to it.
Well you will have to determine why it is leaking. It is just a loose fitting? try tightening it up with a wrench Is there a crack? Is the pipe white PVC (plastic) or copper or even gray metal? If it is any of these you will need to cut it out and replace that section. You might want to consider hiring a plumber.
if it is leaking (green) hydraulic fluid, you have to fix the leak issue, since the brakes are tied into the hydraulic system on that year's model.
Use a pipe cutter to cut the connector about two inches away on all sides. Use a shark pipe connector to replace the copper T-connection with aCPVC connection.