Calling into the shell

[Philip Prindeville <philipp_subx redfish-solutions com>]

I'm trying to take a variable, and perform some substitutions on it 
(kind of like $(subst,,,) in gmake).

The variable looks like:

%define builtin_modules mod_tls:mod_lang:mod_readme:...

=====

%description
ProFTPD is an enhanced FTP server with a focus toward simplicity, security,
and ease of configuration.  It features a very Apache-like configuration
syntax, and a highly customizable server infrastructure, including support for
multiple 'virtual' FTP servers, anonymous FTP, and permission-based directory
visibility.

The base proftpd package installs standalone support. You can install the
proftpd-inetd package to enable inetd/xinetd support.

Likewise, mod_sql_mysql, mod_ldap, etc. can be installed separately to avoid
unnecessary dependencies.

%{?shared_modules:This package supports DSO (shared) modules.}

Intrinsic static modules: %{eval echo "${builtin_modules}" | sed -e 's/:/, /g'}

Optional static modules: %{eval echo "${static_modules}" | sed -e 's/:/, /g'}

Bundled shared modules: %{eval echo "${shared_modules}" | sed -e 's/:/, /g'}

Unbundled (optional) shared modules: ${eval echo "${unbundled_modules}" | sed -e 's/:/, /g'}


=====


What's the proper way to do this?

Thanks!