Load them into an associative array. This will require your shell to be bash 4.x, not /bin/sh
(which, even when a symlink to bash, runs in POSIX compatibility mode).
declare -A props
while read -r; do
[[ $REPLY = *=* ]] || continue
props[${REPLY%%=*}]=${REPLY#*=}
done <input-file.properties
...after which you can access them like so:
echo "${props[this.prop.name]}"
If you want to recursively look up references, then it gets a bit more interesting.
getProp__property_re='[$][{]([[:alnum:].]+)[}]'
getProp() {
declare -A seen=( ) # to prevent endless recursion
declare propName=$1
declare value=${props[$propName]}
while [[ $value =~ $getProp__property_re ]]; do
nestedProp=${BASH_REMATCH[1]}
if [[ ${seen[$nestedProp]} ]]; then
echo "ERROR: Recursive definition encountered looking up $propName" >&2
return 1
fi
value=${value//${BASH_REMATCH[0]}/${props[$nestedProp]}}
done
printf '%s\n' "$value"
}
If we have props
defined as follows (which you could also get by running the loop at the top of this answer with an appropriate input-file.properties
):
declare -A props=(
[glassfish.home.dir]='${app.install.dir}/${glassfish.target}'
[app.install.dir]=/install
[glassfish.target]=target
)
...then behavior is as follows:
bash4-4.4$ getProp glassfish.home.dir
/install/target