Don't ignore "null" values in variable expansions

Replace ${var:-default} with ${var-default}.

I learned something new about shell scripting today.  From bash manual:
===
When not performing substring expansion, using the form described
below (e.g., ‘:-’), Bash tests for a parameter that is unset or null.
Omitting the colon results in a test only for a parameter that is
unset. Put another way, if the colon is included, the operator tests
for both parameter’s existence and that its value is not null; if
the colon is omitted, the operator tests only for existence.
===

The immediate problem I need to fix is handling of
host_aarchXX_excludecheck and host_x86_64_excludecheck parameters
in tcwg-buildfarm.sh.  With ":-" syntax the empty ("null") values are
replaced by defaults, causing GCC testsuite to be ignored on aarchXX
hosts when "--host_aarchXX_excludecheck ''" is given.

There happens to be a single usage ":-" in ${rw:-rw} in
start-container-qemu.sh, where ":-" is actually needed.

Change-Id: Ibc8e070b698e1c76e2161eb65d40639b8cdec1f3

1 files changed, 4 insertions, 4 deletions

diff --git a/tcwg-update-tested.sh b/tcwg-update-tested.sh
index a3111f5e..a68cabc8 100755
--- a/tcwg-update-tested.sh
+++ b/tcwg-update-tested.sh
@@ -7,10 +7,10 @@ convert_args_to_variables "$@"
 
 # Make shellcheck happy and workaround Jenkins not defining variables
 # for empty arguments.
-GIT_COMMIT="${GIT_COMMIT:-HEAD}"
-GIT_COMMIT_1="${GIT_COMMIT_1:-HEAD}"
-GIT_COMMIT_2="${GIT_COMMIT_2:-HEAD}"
-verbose="${verbose:-true}"
+GIT_COMMIT="${GIT_COMMIT-HEAD}"
+GIT_COMMIT_1="${GIT_COMMIT_1-HEAD}"
+GIT_COMMIT_2="${GIT_COMMIT_2-HEAD}"
+verbose="${verbose-true}"
 
 # Jenkins doesn't define variables when parameter value is empty,
 # so enable "set -u" only after above binding of variables.