If pacmd fails, there's no way to check that:
$ pacmd suspend false; echo $?
Welcome to PulseAudio! Use "help" for usage information.
>>> Failed to resume/suspend all sinks: Input/Output error
With pa 5 it is still impossible to tell wether pacmd succeeded:
% pacmd load-module imaginary-module ; echo $?
Module load failed.
It's generally better to use pactl rather than pacmd.
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This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.
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