Setting an argument with bash [duplicate]

Question

I frequently run a simple bash command:

rpm -Uvh --define "_transaction_color 3" myPackage.rpm

which works properly.

But now I'm trying to script it into a bash file, and make it more flexible:

#!/bin/bash
INSTALL_CMD=rpm
INSTALL_OPT="-Uvh --define '_transaction_color 3'"

${INSTALL_CMD} ${INSTALL_OPT} myPackage.rpm

However, this keeps generating the error:

error: Macro % has illegal name (%define)

The error is coming from how --define and the quoted _transaction_color is handled.
I've tried a variety of escaping, different phrasing, even making INSTALL_OPT an array, handled with ${INSTALL_OPT[@]}.

So far, my attempts have not worked.
Clearly, what I want is extremely simple. I'm just not sure how to accomplish it.

How can I get bash to handle my --define argument properly?

Answer 1

The problem is that quotes are not processed after variable substitution. So it looks like you're trying to define a macro named '_transaction_color.

Try using an array:

INSTALL_OPT=(-Uvh --define '_transaction_color 3')

then:

"$INSTALL_CMD" "${INSTALL_OPT[@]}" myPackage.rpm

It's important to put ${INSTALL_OPT[@]} inside double quotes to get the requoting.