Subshell evaluations are not exempt from errexit, so if a command is
not available, `which` will fail and exit the script as a whole.
This causes the helpful error messages to not be printed if they are
tacked on using a `$?` comparison.

Resolve the issue by using chains of logical operators, which are not
subject to the effects of errexit.

Fixes: e37c1877ba5b1 ("scripts/selinux: modernize mdp")
Signed-off-by: Tim Schumacher <tim.schumacher1@huawei.com>
---
 scripts/selinux/install_policy.sh | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
index 24086793b0d8..db40237e60ce 100755
--- a/scripts/selinux/install_policy.sh
+++ b/scripts/selinux/install_policy.sh
@@ -6,27 +6,24 @@ if [ `id -u` -ne 0 ]; then
 	exit 1
 fi
 
-SF=`which setfiles`
-if [ $? -eq 1 ]; then
+SF=`which setfiles` || {
 	echo "Could not find setfiles"
 	echo "Do you have policycoreutils installed?"
 	exit 1
-fi
+}
 
-CP=`which checkpolicy`
-if [ $? -eq 1 ]; then
+CP=`which checkpolicy` || {
 	echo "Could not find checkpolicy"
 	echo "Do you have checkpolicy installed?"
 	exit 1
-fi
+}
 VERS=`$CP -V | awk '{print $1}'`
 
-ENABLED=`which selinuxenabled`
-if [ $? -eq 1 ]; then
+ENABLED=`which selinuxenabled` || {
 	echo "Could not find selinuxenabled"
 	echo "Do you have libselinux-utils installed?"
 	exit 1
-fi
+}
 
 if selinuxenabled; then
     echo "SELinux is already enabled"
-- 
2.43.0

On Mar  7, 2025 Tim Schumacher <tim.schumacher1@huawei.com> wrote:
> 
> Subshell evaluations are not exempt from errexit, so if a command is
> not available, `which` will fail and exit the script as a whole.
> This causes the helpful error messages to not be printed if they are
> tacked on using a `$?` comparison.
> 
> Resolve the issue by using chains of logical operators, which are not
> subject to the effects of errexit.
> 
> Fixes: e37c1877ba5b1 ("scripts/selinux: modernize mdp")
> Signed-off-by: Tim Schumacher <tim.schumacher1@huawei.com>
> ---
>  scripts/selinux/install_policy.sh | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)

Nice catch, merged into selinux/dev, thanks!

--
paul-moore.com