I am unable to run adb shell screenrecord /sdcard/my.mp4
Device specification that i am trying to run this command:
First of all, if you have copied this line from command line, then it seems to be spelling-error:
adb shell screenrecord /sdacrd/my.mp4
Should it not be like adb shell screenrecord /sdcard/my.mp4
?
Are you trying to save this video on your device or on your PC?
Now, to record screen or to capture screenshot, I strongly recommend to use Android Studio as it has inbuilt options to record.
It's here in MacOS: