Hi -
I noticed that -m (-p, --preserve-environment) and -l (- --login) can't be
used together.
Attached is a patch to give a warning if they are and to indicate which
option is used. In the code, I opted for the earlier option ignoring the
later option. In the code --login has precedence over
--preserve-environment.
From 8a74ea72e7718fac9bcf1c33a17f675adb6a1987 Mon Sep 17 00:00:00 2001
From: R. Bernstein <ro...@gnu.org>
Date: Sat, 17 Dec 2011 15:37:48 -0500
Subject: [PATCH] su: Warn that --login and --preserve environment are mutually exclusive
coreutils.texi: document that -l and -m are mutually exclusive.
---
doc/coreutils.texi | 4 ++++
src/su.c | 19 +++++++++++++++++--
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index c26a53d..d874519 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -15636,6 +15636,8 @@ environment variables except @env{TERM}, @env{HOME}, and @env{SHELL}
directory. Prepend @samp{-} to the shell's name, intended to make it
read its login startup file(s).
+Note that this option and the next one @option{-m} are mutually exclusive.
+
@item -m
@itemx -p
@itemx --preserve-environment
@@ -15654,6 +15656,8 @@ is not listed in the file @file{/etc/shells}, or in a compiled-in list
if that file does not exist. Parts of what this option does can be
overridden by @option{--login} and @option{--shell}.
+Note that this option and the previous one @option{-l} are mutually exclusive.
+
@item -s @var{shell}
@itemx --shell=@var{shell}
@opindex -s
diff --git a/src/su.c b/src/su.c
index b1ba2a7..75931d7 100644
--- a/src/su.c
+++ b/src/su.c
@@ -400,6 +400,7 @@ main (int argc, char **argv)
char *shell = NULL;
struct passwd *pw;
struct passwd pw_copy;
+ static bool seen_login_change_env = false ;
initialize_main (&argc, &argv);
set_program_name (argv[0]);
@@ -427,12 +428,26 @@ main (int argc, char **argv)
break;
case 'l':
- simulate_login = true;
+ if (seen_login_change_env && !simulate_login) {
+ fprintf (stderr, _("%s: already seen --preserve-environment; --login ignored.\n"),
+ program_name);
+ } else {
+ simulate_login = true;
+ seen_login_change_env = true;
+ }
+
break;
case 'm':
case 'p':
- change_environment = false;
+ if (seen_login_change_env && change_environment) {
+ fprintf (stderr, _("%s: already seen option --login; --preserve-environment ignored.\n"),
+ program_name);
+ } else {
+ change_environment = false;
+ seen_login_change_env = true;
+ }
+
break;
case 's':
--
1.7.4.1
