We are calling bash script from Jenkinsfile which evaluates boolean parameter for running authentication script:
#!/bin/bash -eu
some case statements
esac
$APP_PARAM:-} && key_aliase="xyz/aaa"
some parameter set
call another shellscript
and wondering what $APP_PARAM:-} && key_aliase="xyz/aaa" means. APP_PARAM is boolean parameter with default value false.
First, it's a typo for
${APP_PARAM:-} && keyaliase="xyzzy/aaa"
The result is that either $APP_PARAM expands to a program to run, and key_aliase is set only if the program succeeds, or the parameter expands to an empty string which, since it is unquoted, becomes a "null" command that is considered to succeed unconditionally.
Given that ${APP_PARAM} and ${APP_PARAM:-} produce the same result when expanded, I assume that the script uses set -u to exit on any attempt to expand an undefined parameter. The latter form expands to an empty string instead of triggering the exit.
