This makes mk use the mkfile specified in $MKFILE
when there is no mkfile in the current directory.

Notes:
Mon Mar 15 12:47:36 EST 2004 rsc
    I'm not convinced that this is a good idea.
    I admit that it provides functionality that is 
    otherwise hard to come by, but it just feels
    kludgy.
    


Reference: /n/sources/patch/sorry/defaultmkfile
Date: Mon Apr  5 23:23:13 CES 2004
Reviewed-by: rsc

--- /sys/src/cmd/mk/main.c	Mon Apr  5 23:23:13 2004
+++ /sys/src/cmd/mk/main.c	Mon Apr  5 23:23:13 2004
@@ -1,6 +1,7 @@
 #include	"mk.h"
 
 #define		MKFILE		"mkfile"
+#define		MKFILEVAR	"MKFILE"
 
 static char *version = "@(#)mk general release 4 (plan 9)";
 int debug;
@@ -34,6 +35,7 @@
 	Biobuf tb;
 	Bufblock *buf;
 	Bufblock *whatif;
+	char	*skel;
 
 	/*
 	 *  start with a copy of the current environment variables
@@ -172,6 +174,14 @@
 	if(f == files){
 		if(access(MKFILE, 4) == 0)
 			parse(MKFILE, open(MKFILE, 0), 0);
+		else {
+			skel = getenv(MKFILEVAR);
+			if (skel != nil){
+				if (access(skel, 4) == 0)
+					parse(skel, open(skel, 0), 0);
+				free(skel);
+			}
+		}
 	} else
 		for(ff = files; ff < f; ff++)
 			parse(*ff, open(*ff, 0), 0);
--- /sys/man/1/mk	Mon Apr  5 23:23:13 2004
+++ /sys/man/1/mk	Mon Apr  5 23:23:13 2004
@@ -53,7 +53,13 @@
 determines how many targets may be updated simultaneously;
 Plan 9 sets
 .B $NPROC
-automatically to the number of CPUs on the current machine.
+automatically to the number of CPUs on the current machine. The
+variable
+.B $MKFILE
+may be set to indicate which
+.B mkfile
+should be read if there is no one in the current
+directory.
 .PP
 Options are:
 .TP \w'\fL-d[egp]\ 'u