Improve shell documentation:

* Consistently misspell built-in as builtin.

* Add a builtin(1) manpage and create builtin(1) MLINKS for all shell
  builtin commands for which no standalone utility exists.  These MLINKS
  replace those that were created for csh(1).

* Add appropriate xrefs for builtin(1) to the csh(1) and sh(1) manpages,
  as well as to the manpages of standalone utilities which are supported
  as shell builtin commands in at least one of the shells. In such
  manpages, explain that similar functionality may be provided as a
  shell builtin command.

* Improve sh(1)'s description of the cd builtin command. Csh(1) already
  describes it adequately. Replace the cd(1) manpage with a builtin(1)
  MLINKS link.

* Clean up some mdoc problems: use Xr instead of literal "foo(n)"; use
  Ic instead of Xr for shell builtin commands.

* Undo English contractions.

Reviewed by:	mpp, rgrimes

6 files changed, 51 insertions, 33 deletions

diff --git a/usr.bin/login/login.1 b/usr.bin/login/login.1
index 2ee22ef..3d1a9c7 100644
--- a/usr.bin/login/login.1
+++ b/usr.bin/login/login.1
@@ -143,13 +143,12 @@ The login class also controls the maximum and current process resource
 limits granted to a login, process priorities and many other aspects of
 a user's login environment.
 .Pp
-The standard shells,
-.Xr csh 1
-and
-.Xr sh 1 ,
-do not fork before executing the
+Some shells may provide a builtin
 .Nm
-utility.
+command which is similar or identical to this utility. Consult
+the
+.Xr builtin 1
+manual page.
 .Sh FILES
 .Bl -tag -width /var/mail/userXXX -compact
 .It Pa /etc/fbtab
@@ -180,7 +179,9 @@ makes login quieter
 configure authentication services
 .El
 .Sh SEE ALSO
+.Xr builtin 1 ,
 .Xr chpass 1 ,
+.Xr csh 1 ,
 .Xr passwd 1 ,
 .Xr rlogin 1 ,
 .Xr skey 1 ,
diff --git a/usr.bin/nice/nice.1 b/usr.bin/nice/nice.1
index 2531a9c..b017179 100644
--- a/usr.bin/nice/nice.1
+++ b/usr.bin/nice/nice.1
@@ -73,6 +73,13 @@ Negative numbers are expressed as
 The returned exit status is the exit value from the
 command executed by
 .Nm nice .
+.Pp
+Some shells may provide a builtin
+.Nm
+command which is similar or identical to this utility. Consult
+the
+.Xr builtin 1
+manual page.
 .Sh EXAMPLES
 .Pp
 $ nice -5 date
@@ -89,6 +96,7 @@ Execute command
 at priority -19 assuming the priority of the
 shell is 0 and you are the super-user.
 .Sh SEE ALSO
+.Xr builtin 1 ,
 .Xr csh 1 ,
 .Xr idprio 1 ,
 .Xr rtprio 1 ,
@@ -100,21 +108,3 @@ A
 .Nm
 command appeared in
 .At v6 .
-.Sh BUGS
-.Nm Nice
-is particular to
-.Xr sh  1  .
-If you use
-.Xr csh  1  ,
-then commands executed with ``&'' are automatically immune to hangup
-signals while in the background.
-.Pp
-.Nm Nice
-is built into
-.Xr csh  1
-with a slightly different syntax than described here.  The form
-.Ql nice +10
-nices to positive nice, and
-.Ql nice \-10
-can be used
-by the super-user to give a process more of the processor.
diff --git a/usr.bin/nohup/nohup.1 b/usr.bin/nohup/nohup.1
index 1fcc7ef..8f137e7 100644
--- a/usr.bin/nohup/nohup.1
+++ b/usr.bin/nohup/nohup.1
@@ -68,6 +68,13 @@ as the standard output.
 .Nm Nohup
 exits 1 if an error occurs, otherwise the exit status is that of
 .Ar command  .
+.Pp
+Some shells may provide a builtin
+.Nm
+command which is similar or identical to this utility. Consult
+the
+.Xr builtin 1
+manual page.
 .Sh ENVIRONMENT
 The following variable is utilized by
 .Nm nohup .
@@ -82,6 +89,8 @@ utility uses the directory named by
 to create the file.
 .El
 .Sh SEE ALSO
+.Xr builtin 1 ,
+.Xr csh 1 ,
 .Xr signal 3
 .Sh STANDARDS
 The
diff --git a/usr.bin/printf/printf.1 b/usr.bin/printf/printf.1
index 665d28f..153990b 100644
--- a/usr.bin/printf/printf.1
+++ b/usr.bin/printf/printf.1
@@ -250,11 +250,21 @@ Print a `%'; no argument is used.
 In no case does a non-existent or small field width cause truncation of
 a field; padding takes place only if the specified field width exceeds
 the actual width.
+.Pp
+Some shells may provide a builtin
+.Nm
+command which is similar or identical to this utility. Consult
+the
+.Xr builtin 1
+manual page.
 .Sh RETURN VALUES
 .Nm Printf
 exits 0 on success, 1 on failure.
 .Sh SEE ALSO
-.Xr printf 3
+.Xr builtin 1 ,
+.Xr csh 1 ,
+.Xr printf 3 ,
+.Xr sh 1
 .Sh HISTORY
 The
 .Nm
diff --git a/usr.bin/time/time.1 b/usr.bin/time/time.1
index 4d29566..196042c 100644
--- a/usr.bin/time/time.1
+++ b/usr.bin/time/time.1
@@ -90,14 +90,12 @@ Makes
 output POSIX.2 compliant (each time is printed on its own line).
 .El
 .Pp
-Most shells (including
-.Xr csh 1 )
-have their own and syntactically different builtin version of
-.Nm time .
-The command described here
-is available as
-.Pa /usr/bin/time
-to users of those shells.
+Some shells may provide a builtin
+.Nm
+command which is similar or identical to this utility.  Consult
+the
+.Xr builtin 1
+manual page. 
 .Sh DIAGNOSTICS
 If
 .Ar command
@@ -115,6 +113,7 @@ If
 encounters any other error, the exit status is between 1 and 125
 included.
 .Sh SEE ALSO
+.Xr builtin 1 ,
 .Xr csh 1 ,
 .Xr getrusage 2 ,
 .Xr wait 2
diff --git a/usr.bin/which/which.1 b/usr.bin/which/which.1
index e9ae9d3..97daca5 100644
--- a/usr.bin/which/which.1
+++ b/usr.bin/which/which.1
@@ -52,12 +52,21 @@ of each).
 .It Fl s
 No output, just return 0 if any of the executables are found, or 1 if
 none are found.
+.Pp
+Some shells may provide a builtin
+.Nm
+command which is similar or identical to this utility.  Consult
+the
+.Xr builtin 1
+manual page. 
 .Sh HISTORY
 The
 .Nm
 command first appeared in
 .Fx 2.1 .
 .Sh SEE ALSO
+.Xr builtin 1 ,
+.Xr csh 1 ,
 .Xr find 1 ,
 .Xr locate 1 ,
 .Xr perl 1 ,