New global option --eprefix

* bin/eselect.in: New global option --eprefix.
(es_do_help): Document it.
* doc/user-guide.txt:
* man/eselect.1: Document the --eprefix option.

Signed-off-by: Ulrich Müller <ulm@gentoo.org>

4 files changed, 32 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 41d4bab..b442b8b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2023-02-26  Ulrich Müller  <ulm@gentoo.org>
+
+	* bin/eselect.in: New global option --eprefix.
+	(es_do_help): Document it.
+	* doc/user-guide.txt:
+	* man/eselect.1: Document the --eprefix option.
+
 2023-02-26  James Le Cuirot  <chewi@gentoo.org>
 
 	* bin/eselect.in: Allow EPREFIX to be overridden for manipulating
diff --git a/bin/eselect.in b/bin/eselect.in
index 6a0fdbc..8afbd7e 100755
--- a/bin/eselect.in
+++ b/bin/eselect.in
@@ -1,6 +1,6 @@
 #!@BASH@
 # -*-eselect-*-  vim: ft=eselect
-# Copyright (c) 2005-2022 Gentoo Authors
+# Copyright (c) 2005-2023 Gentoo Authors
 #
 # This file is part of the 'eselect' tools framework.
 #
@@ -91,6 +91,8 @@ es_do_help() {
 	write_kv_list_entry "--brief" "Make output shorter"
 	write_kv_list_entry "--colour=<yes|no|auto>" \
 		"Enable or disable colour output (default 'auto')"
+	write_kv_list_entry "--eprefix=<path>" \
+		"Override the EPREFIX variable for a cross-prefix build"
 	write_kv_list_entry "--root=<path>" \
 		"The target root path for eselect's operations"
 	echo
@@ -152,6 +154,12 @@ while [[ ${1##--} != "$1" ]]; do
 			[[ -z ${action} ]] || die -q "Too many parameters"
 			action=${1##--}
 			;;
+		eprefix=*|eprefix)
+			[[ ${1#*=} == "$1" ]] && die -q "Option $1 requires an argument"
+			# set EPREFIX and recalculate EROOT
+			EPREFIX=${1#*=}
+			EROOT="${ROOT%${EPREFIX:+/}}${EPREFIX}"
+			;;
 		root=*|root)
 			[[ ${1#*=} == "$1" ]] && die -q "Option $1 requires an argument"
 			# set ROOT and recalculate EROOT
diff --git a/doc/user-guide.txt b/doc/user-guide.txt
index 16c2629..2932b7f 100644
--- a/doc/user-guide.txt
+++ b/doc/user-guide.txt
@@ -91,11 +91,12 @@ eselect should be called as shown below: ::
         eselect [<global-options>] <module> <action> <options>
 
 eselect features consistently named actions among most of its modules.
-There are only three global options as of now; --brief, which makes
+There are only four global options as of now; --brief, which makes
 eselect's output shorter (e.g., to use it as input for other programs);
---colour, which controls coloured output; and --root, which specifies
-the path that eselect should use as the target root filesystem for its
-operations.
+--colour, which controls coloured output; --eprefix, which allows to
+override the EPREFIX variable for a cross-prefix build; and --root,
+which specifies the path that eselect should use as the target root
+filesystem for its operations.
 
 The following are standard action names -- each module may provide a
 subset of these actions:
diff --git a/man/eselect.1 b/man/eselect.1
index fad2aac..a331dee 100644
--- a/man/eselect.1
+++ b/man/eselect.1
@@ -1,8 +1,8 @@
 .\" -*- coding: utf-8 -*-
-.\" Copyright 2005-2022 Gentoo Authors
+.\" Copyright 2005-2023 Gentoo Authors
 .\" Distributed under the terms of the GNU GPL version 2 or later
 .\"
-.TH ESELECT 1 "January 2022" "Gentoo Linux" eselect
+.TH ESELECT 1 "February 2023" "Gentoo Linux" eselect
 .SH NAME
 eselect \- Gentoo's multi\-purpose configuration and management tool
 .SH SYNOPSIS
@@ -33,6 +33,15 @@ The default is
 for which colour output is enabled only if standard output is
 connected to a terminal.
 .TP
+.BI \-\-eprefix= path
+The
+.I path
+that eselect should use as the offset-prefix path for its operations.
+Only relevant for a cross-prefix build.  If neither this option nor the
+.I EPREFIX
+environment variable are specified, the hardcoded prefix of the build
+host is used as a default.
+.TP
 .BI \-\-root= path
 The
 .I path