Simon Bridge is absolutely right: "You don't". You need to take whatever you were doing in the .bat file, and completely re-write it to do the equivalent in Linux.
In order to do this (as b0uncer and chrism01 both pointed out), you need to know two things:
a) Some basic "shell script" syntax (for example, "bash" or "sh" syntax)
b) Some basic Linux commands (for example, "ls", "cat", ..., "awk", "sed", ...)
Here (in addition to the links already cited) is another beginner's tutorial that might help :