[PATCH] um: Makefile: use bash from the environment

[Yueh-Shun Li]

Set Makefile SHELL to bash instead of /bin/bash for better portability.

Some systems do not install binaries to /bin, and therefore do not
provide /bin/bash. OS distributions such as NixOS and Guix System
intentionally avoid implementing the Filesystem Hierarchy Standard (FHS).

The recipies inside arch/um/Makefile don't require top-level Bash to
build, and setting "SHELL" to "bash" makes Make pick the Bash executable
from the environment[2], hence this patch.

Signed-off-by: Yueh-Shun Li <shamrocklee@xxxxxxxxxx>
---
 arch/um/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/um/Makefile b/arch/um/Makefile
index 82f05f250634..904e2b990963 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -20,7 +20,7 @@ endif
 ARCH_DIR := arch/um
 # We require bash because the vmlinux link and loader script cpp use bash
 # features.
-SHELL := /bin/bash
+SHELL := bash
 
 MODE_INCLUDE	+= -I$(srctree)/$(ARCH_DIR)/include/shared/skas
 
-- 
2.42.0