1 make: "varmod-shell.mk" line 25: warning: while evaluating "${:!echo word; (exit 13)!} != "word"": Command "echo word; (exit 13)" exited with status 13 2 make: "varmod-shell.mk" line 29: warning: while evaluating "${:Uprevious value:!echo word; (exit 13)!} != "word"": Command "echo word; (exit 13)" exited with status 13 3 Global: _ = # (empty) 4 Var_Parse: ${:!echo word; ${:U(exit 13)}!} (eval-keep-dollar-and-undefined) 5 Evaluating modifier ${:!...} on value "" (eval-keep-dollar-and-undefined, undefined) 6 Modifier part: "echo word; (exit 13)" 7 Capturing the output of command "echo word; (exit 13)" 8 make: "varmod-shell.mk" line 36: warning: while evaluating "${:!echo word; ${:U(exit 13)}!}": Command "echo word; (exit 13)" exited with status 13 9 Result of ${:!echo word; ${:U(exit 13)}!} is "word" (eval-keep-dollar-and-undefined, defined) 10 Global: _ = word 11 Global: .MAKEFLAGS = -r -k -d v -d 12 Global: .MAKEFLAGS = -r -k -d v -d 0 13 exit status 0 14