I've grown fond of using a generator-like pattern between functions in my shell scripts. Something like this:
parse_commands /da/cmd/file | process_commands
However, the basic problem with this pattern is that if parse_command encounters an error, the only way I have found to notify process_command that it failed is by explicitly telling it (e.g. echo "FILE_NOT_FOUND"). This means that every potentially faulting operation in parse_command would have to be fenced.
Is there no way process_command can detect that the left side exited with a non-zero exit code?