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

1 files changed, 9 insertions, 0 deletions

diff --git a/usr.bin/nohup/nohup.1 b/usr.bin/nohup/nohup.1
index 1fcc7efd3a21..8f137e784b6b 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