5.1. Parsing Commands

Following a make target, lines whose first character is a tab are assumed to be commands (unless the previous line was continued with a backslash). GNU make tries to be as smart as possible when handling tabs in other contexts. For instance, when there is no possible ambiguity, comments, variable assignments, and include directives may all use a tab as their first character. If make reads a command line that does not immediately follow a target, an error message is displayed:

makefile:20: *** commands commence before first target.  Stop.