[Help-bash] Sourcing only valid variables from a script configuration file

[Jesse Molina]

Hello everyone

I am trying to do something that bash doesn't seem to be very good at. 
I'll admit right now that the best advice for myself would be to 
re-write my script in python or perl.  However, I really wanted to do 
this in bash for educational purposes.  Thus, I have created a monster.

I have a script which reads a configuration file, which is simply made 
up of comments and variable assignments.

'source' is the obvious correct command to bring this configuration file 
into the script.  However, I want input validation and other protections 
against commands and other non-expected data from being in the 
configuration file.

In this configuration file, the variables are known and expected.  If an 
expected variable is missing or invalid, we exit with an error.  If 
addition non-variable or comment data is in the configuration file, we 
should also exit with an error.

I will probably end up writing a function to validate the stat() on the 
file, grep for anything invalid, make sure there are no command 
substitution or similar nonsense within the valid variables, and the like.

Does anyone have any helpful advice for me on this subject beyond what I 
already know here?



FYI I spent an hour or two googling around and came up with the 
following articles.  Mostly, it was confirmed that there isn't a 
built-in to make this easy, which disappointed me:

http://lcorg.blogspot.com/2010/06/using-configuration-files-with-shell.html

http://stackoverflow.com/questions/4434797/read-a-config-file-in-bash-without-using-source

http://wiki.bash-hackers.org/howto/conffile

https://bbs.archlinux.org/viewtopic.php?id=39451

http://stackoverflow.com/questions/5983558/reading-a-config-file-from-a-shell-script



--
# Jesse Molina
# Mail = address@hidden
# Cell = 1-602-323-7608