env(1): grow -L user/class and -U user/class options

This allows one to set the environment of the specified user either from
login.conf alone (-L) or both login.conf and ~/.login_conf if present (-U).

This is a supporting feature to allow service(8) to pull in the environment
of the "daemon" class before invoking the rc script.

This is a part of D21481.

Submitted by:	Andrew Gierth < andrew_tao173.riddles.org.uk>

1 files changed, 32 insertions, 2 deletions

diff --git a/usr.bin/env/env.1 b/usr.bin/env/env.1
index bb3e4e719526..4584fde75756 100644
--- a/usr.bin/env/env.1
+++ b/usr.bin/env/env.1
@@ -31,7 +31,7 @@
 .\" From FreeBSD: src/usr.bin/printenv/printenv.1,v 1.17 2002/11/26 17:33:35 ru Exp
 .\" $FreeBSD$
 .\"
-.Dd November 7, 2019
+.Dd January 19, 2020
 .Dt ENV 1
 .Os
 .Sh NAME
@@ -40,6 +40,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl 0iv
+.Op Fl L Ns | Ns Fl U Ar user Ns Op / Ns Ar class
 .Op Fl P Ar altpath
 .Op Fl S Ar string
 .Op Fl u Ar name
@@ -76,6 +77,28 @@ The environment inherited
 by
 .Nm
 is ignored completely.
+.\"	-L | -U
+.It Fl L | Fl U Ar user Ns Op / Ns Ar class
+Add the environment variable definitions from
+.Xr login.conf 5
+for the specified user and login class to the environment, after
+processing any
+.Fl i
+or
+.Fl u
+options, but before processing any
+.Ar name Ns = Ns Ar value
+options.
+If
+.Fl L
+is used, only the system-wide
+.Pa /etc/login.conf.db
+file is read; if
+.Fl U
+is used, then the specified user's
+.Pa ~/.login_conf
+is read as well.
+The user may be specified by name or by uid.
 .\"	-P
 .It Fl P Ar altpath
 Search the set of directories as specified by
@@ -450,6 +473,7 @@ option as a synonym for
 .Xr printenv 1 ,
 .Xr sh 1 ,
 .Xr execvp 3 ,
+.Xr login.conf 5 ,
 .Xr environ 7
 .Sh STANDARDS
 The
@@ -457,7 +481,7 @@ The
 utility conforms to
 .St -p1003.1-2001 .
 The
-.Fl P , S , u
+.Fl 0 , L , P , S , U , u
 and
 .Fl v
 options are non-standard extensions supported by
@@ -474,6 +498,12 @@ and
 .Fl v
 options were added in
 .Fx 6.0 .
+The
+.Fl 0 , L
+and
+.Fl U
+options were added in
+.Fx 13.0 .
 .Sh BUGS
 The
 .Nm