Many small edits.

man/man1/mk.1

@@ -1,21 +1,4 @@
 .TH MK 1
-.de EX
-.nf
-.ft B
-..
-.de EE
-.fi
-.ft R
-..
-.de LR
-.if t .BR \\$1 \\$2
-.if n .RB ` \\$1 '\\$2
-..
-.de L
-.nh
-.if t .B \\$1
-.if n .RB ` \\$1 '
-..
 .SH NAME
 mk, membername \- maintain (make) related files
 .SH SYNOPSIS
@@ -313,6 +296,7 @@ and any command line assignment as an argument to
 .IR mk .
 A variable assignment argument overrides the first (but not any subsequent)
 assignment to that variable.
+.PP
 The variable
 .B MKFLAGS
 contains all the option arguments (arguments starting with
@@ -324,6 +308,45 @@ and
 contains all the targets in the call to
 .IR mk .
 .PP
+The variable
+.B MKSHELL
+contains the shell command line
+.I mk
+uses to run recipes.
+If the first word of the command ends in
+.B rc
+or
+.BR rcsh ,
+.I mk
+uses
+.IR rc (1)'s
+quoting rules; otherwise it uses
+.IR sh (1)'s.
+The
+.B MKSHELL
+variable is consulted when the mkfile is read, not when it is executed,
+so that different shells can be used within a single mkfile:
+.IP
+.EX
+MKSHELL=$PLAN9/bin/rc
+use-rc:V:
+	for(i in a b c) echo $i
+
+MKSHELL=sh
+use-sh:V:
+	for i in a b c; do echo $i; done
+.EE
+.LP
+Mkfiles included via
+.B <
+or
+.B <|
+.RI ( q.v. )
+see their own private copy of
+.BR MKSHELL ,
+which always starts set to
+.B sh .
+.PP
 Dynamic information may be included in the mkfile by using a line of the form
 .IP
 \fR<|\fIcommand\fR \fIargs\fR
@@ -510,6 +533,7 @@ archives.
 .I Membername
 echoes just the member names of a list of aggregate names.
 It is useful in recipes like:
+.IP
 .EX
 OFILES=a.o b.o
 libc.a(%):N: %
@@ -647,7 +671,7 @@ x.tab.h:Pcmp -s:	y.tab.h
 .EE
 .SH SEE ALSO
 .IR sh (1),
-.IR regexp9 (7)
+.IR regexp (7)
 .PP
 A. Hume,
 ``Mk: a Successor to Make''
@@ -664,19 +688,18 @@ It was later ported to Plan 9.
 This software is a port of the Plan 9 version back to Unix.
 .SH BUGS
 Identical recipes for regular expression meta-rules only have one target.
-.br
+.PP
 Seemingly appropriate input like
 .B CFLAGS=-DHZ=60
 is parsed as an erroneous attribute; correct it by inserting
 a space after the first 
 .LR = .
-.br
+.PP
 The recipes printed by
 .I mk
 before being passed to
-.I sh
+the shell
 for execution are sometimes erroneously expanded
 for printing.  Don't trust what's printed; rely
-on what
-.I sh
+on what the shell
 does.