Merging Bash sources

[Simon Wistow]

On Wed, Nov 11, 2009 at 01:03:08AM +0000, me said:
> Is there an easy way to say "source this config file but don't override 
> any variable already set?" or some sort of standard recipe? Or amy I 
> going to have to write something that reads the config file line by 
> line, splits out any variable name left of a '=' checks to see if it's 
> set and then evals the line? Cos that's potentially prone to failure.

Something like this in fact:

% cat try.sh

#!/usr/local/bin/bash
    
function loadConfig {
    for line in `cat $1`;
    do
        name=`echo "$line" | cut -d '=' -f 1`
        if [[ -z `echo "$line" | grep '='` || -z "$name" ]]; 
        then
            continue;
        fi
        value=`eval echo \\$${name}`
        if [[ -z ${value} ]];
        then
            eval ${line}
        fi
    done
}

config="try.conf"
echo "Config is: "
cat ${config}
echo ""
echo ""

foo="a"
loadConfig ${config}

echo "Variables are now:";
echo "foo=${foo}"
echo "bar=${bar}"


% ./try.sh
Config is: 
foo="quirka"
# foo
bar="fleeg"


Variables are now:
foo=a
bar=fleeg