This is what we use, for what it's worth.
 [rsc] --rw-rw-r-- M 191333 glenda sys 4409 Sep 22 13:30 sys/lib/dist/mkfile
	/n/sourcesdump/2005/0922/plan9/sys/lib/dist/mkfile:109,114 - 
	/n/sourcesdump/2005/0923/plan9/sys/lib/dist/mkfile:109,115
	  		dd=$"date
	  		mail -s 'nightly build differences '^$dd 9trouble <checkbuild.out
	  	}
	+ 	status=''
	  
	  scansources-mail:V:
	  	dd=`{date}
	/n/sourcesdump/2005/0922/plan9/sys/lib/dist/mkfile:123,126 - 
	/n/sourcesdump/2005/0923/plan9/sys/lib/dist/mkfile:124,140
	  		mail -s 'WRITABLE FILES ON SOURCES '^$dd 9trouble </sys/lib/dist/writable
	  	}
	  	status=''
	- 
	+ 	cd /n/sources/plan9; /usr/rsc/bin/$cputype/lsr -t -d /n/sources/plan9 | awk '$2 ~ /[2367][^2367].$/' >/sys/lib/dist/writable
	+ 	if(test -s /sys/lib/dist/writable){
	+ 		dd=`{date}
	+ 		dd=$"date
	+ 		mail -s 'non-group-writable files on sources'^$dd 9trouble </sys/lib/dist/writable
	+ 	}
	+ 	status=''
	+ 	/usr/rsc/bin/$cputype/lsr -t -d /sys /lib | awk '$2 ~ /[2367][^2367].$/' >/sys/lib/dist/writable
	+ 	if(test -s /sys/lib/dist/writable){
	+ 		dd=`{date}
	+ 		dd=$"date
	+ 		mail -s 'non-group-writable files on fs '^$dd 9trouble </sys/lib/dist/writable
	+ 	}
	+ 	status=''