fix(ensure-shutdown): apply timeout default under nounset#369
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The script runs under 'set -o nounset'. When no config file assigns
ENSURE_SHUTDOWN_TIMEOUT, the bare "${ENSURE_SHUTDOWN_TIMEOUT}" in the
fallback guard raises an unbound-variable error and aborts before the
guard can apply the default, so ExecStart never starts the shutdown
monitor. Add the ':-' default in the -z test so the guard runs and
falls back to 30. The sibling emerg-shutdown wrapper avoids this by
pre-initializing its config variables before sourcing.
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Summary
ensure-shutdown's built-inENSURE_SHUTDOWN_TIMEOUTfallback is unreachable underset -o nounset. When no config file assigns the variable, the guard aborts the script instead of defaulting to 30, so the forced-shutdown watchdog (ExecStart) never starts.Changes
[ -z "${ENSURE_SHUTDOWN_TIMEOUT}" ]with no:-default. Undernounset, expanding the unset variable raisesunbound variableand exits before the=30fallback can run. Add the:-default (${ENSURE_SHUTDOWN_TIMEOUT:-}) so the guard evaluates and applies the default. Theis_whole_numbercall on the next line is unchanged — it is only reached when the variable is set.Testing
bash -non the patched script — OK.set -o nounset, variable unset: pre-fix[ -z "${VAR}" ]→VAR: unbound variable, exit 127, fallback never runs; post-fix[ -z "${VAR:-}" ]→ prints the fallback branch, exit 0.Notes for reviewers
etc/security-misc/emerg-shutdown/30_security_misc.confsetsENSURE_SHUTDOWN_TIMEOUT=30, so this only bites a config that no longer assigns it (e.g. an admin edits the conffile trusting the script's advertised default). The siblingemerg-shutdownwrapper avoids the same trap by pre-initializing its config variables before sourcing.