Since the implementation of Arrays in Bash is somewhat lacking compared to higher level programming languages (only one-dimensional), and hash lists require a bit of work to set up, you may run into a situation where you have a small list of key/value pairs that are both variable and you need to store.
There are various solutions for the problem, e.g. creating two arrays (one for the keys, one for the values, and combining them by using the same index values for the entries), or using the functions from the link above to build a hash list. For me the easiest way to solve the problem, if I only have a few variables and don’t want to bloat the code, is to (mis)use declare. declare is intended for setting the type of a variable (constant, array, integer,…), but has the nice side affect that you can use variables in the key name, and you can set the value of the variable.
usage:
declare ${Key}=${Value}
Example:
$File_Config is variable holding the name of a configfile, the content of the file could look like this:
foo:one
bar:three
foobar:bignumber
Snippet:
1 2 3 4 5 6 7 8 9 10 11 12 13 | if [[ -e "${File_Config}" ]] then while read line do Key="${line%%:*}" # chop off everything after the first : Value="${line#*:}" # chop off everything before the first : Value="$(echo ${Value}|sed 's#^ +##g;s# +$##g')" # chop off any excess whitespace if [[ "${Key}" != "" && "${Value}" != "" ]] # only continue if we have something to do then declare Configuration_${Key}="${Value}" fi done < "${File_Config}" fi |
after the snippet has read the configfile, you can use $Configuration_foo, $Configuration_bar and $Configuration_foobar in your script. The keynames could also have came from a mysql query, array, command line args, …