I recorded two finger pinch with getevent but when replaying it the touch cannot release

Question

I am trying to write some automation script for the Android emulator I am using. The emulator does provide simulation of pinches with keyboard and trackpad, but I would like to do it through the Android console, so I recorded the pinch with getevent, converted it to decimal and replay it with sendevent. I do observed the pinch but when it is done, the touch is not released and this mess up the simulations later on. I observe that if BTN_TOUCH UP event is send along with the pinch, it won't work. I cannot even do things like sh zoom-out.sh && sleep 1 && sh release.sh (assuming that I have the scripts to zoom out and releasing the touch in these 2 files). The only thing that works is through calling sh zoom-out.sh and then sh release.sh on a new line, which is wried to me.