git: 39db0c62b210 - stable/13 - grep.1: Add an ENVIRONMENT section

The branch stable/13 has been updated by gbe (doc committer):

URL: https://cgit.FreeBSD.org/src/commit/?id=39db0c62b2104753c196fd1cb7257f33a95ce10f

commit 39db0c62b2104753c196fd1cb7257f33a95ce10f
Author:     Jose Luis Duran <jlduran@gmail.com>
AuthorDate: 2022-12-18 07:22:24 +0000
Commit:     Gordon Bergling <gbe@FreeBSD.org>
CommitDate: 2022-12-28 15:28:32 +0000

    grep.1: Add an ENVIRONMENT section
    
    Document the environment variables used by grep(1).
    
    Reviewed by:    pauamma, kevans
    Differential Revision:  https://reviews.freebsd.org/D37726
    
    (cherry picked from commit cf7fe60e63bb8c44d929490ff9c74eb94dde8af7)
---
 usr.bin/grep/grep.1 | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/usr.bin/grep/grep.1 b/usr.bin/grep/grep.1
index 7f0c82b7ad6d..f64adc7fadfd 100644
--- a/usr.bin/grep/grep.1
+++ b/usr.bin/grep/grep.1
@@ -30,7 +30,7 @@
 .\"
 .\"	@(#)grep.1	8.3 (Berkeley) 4/18/94
 .\"
-.Dd April 17, 2021
+.Dd December 18, 2022
 .Dt GREP 1
 .Os
 .Sh NAME
@@ -440,6 +440,22 @@ read from standard input.
 This includes both
 .Fl f
 and file arguments.
+.Sh ENVIRONMENT
+The following environment variables affect the execution of
+.Nm :
+.Bl -tag -width "GREP_OPTIONS"
+.It Ev GREP_COLOR
+This variable specifies the color used to highlight matched (non-empty) text.
+.It Ev GREP_OPTIONS
+This variable specifies default options
+to be placed in front of any explicit options.
+It may cause problems with portable scripts.
+.It Ev TERM
+This variable specifies the type name of the terminal, console or display-device
+type to be used.
+See
+.Xr term 7 .
+.El
 .Sh EXIT STATUS
 The
 .Nm grep