[gentoo-dev] interesting bit of bash

[Aron Griffis <agriffis@gentoo.org>]

I don't know if this would be useful to anybody, but while looking into
a bug, I came up with a method to determine what variables are set by a
file such as make.conf or /etc/conf.d/*

    vars_in_file() {
        local _file=$1
        ( eval "`export | sed 's/-/+/'`"  # need double-quotes
          set -a                          # export all new vars
          . $_file                        # load up the vars
          export | sed -n 's/^declare -x \(.*\)=".*/\1/p' )
    }

This function will list the variables set in a file, for example

    $ vars_in_file /etc/make.conf
    ACCEPT_KEYWORDS
    CFLAGS
    CHOST
    CONFIG_PROTECT_MASK
    CXXFLAGS
    DISTCC_HOSTS
    DISTDIR
    FEATURES
    GENTOO_MIRRORS
    MAKEOPTS
    PORTAGE_NICENESS
    PORTDIR
    USE

    $ vars_in_file /etc/conf.d/net
    gateway
    iface_eth0

The listing should always be correct since the file is being interpreted
(and executed) by bash.

Aron

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