Dynamic Variable assignmenet in ShellScript

I have two variables in my bash script

CAR_PRICE=50000
BIKE_PRICE=20000

I am passing a command line argument while executing my .sh shell script file.

--vehicletype CAR  or --vehicletype BIKE

I am able to read the vehicletype value in the script and store in another varible

VEHICLE_TYPE=<VALUE PASSED FROM COMMAND LINE ARG i.e CAR/BIKE

Now I am trying to dynamically read CAR_PRICE or BIKE_PRICE using following syntax

${${VEHICLE_TYPE}_PRICE}

to get the values of the params subtituting the first part of the variable dynamically based on the value passwed ie but it is throwing Bad Substitution error.

I tried several ways but nothing seem to work. I am new to shell script and not sure if such dynamic substitution is supported in bash script.

Any pointers would be helpful.

CodePudding user response：

You can use indirect variable reference in bash:

CAR_PRICE=50000
BIKE_PRICE=20000
VEHICLE_TYPE='CAR'
var="${VEHICLE_TYPE}_PRICE"

# variable name
echo "$var"
# variable value
echo "${!var}"

Output:

CAR_PRICE
50000

CodePudding user response：

You can use price=${VEHICLE_TYPE}_PRICE; echo "${!price}". However, associative arrays are a better tool for this job:

declare -A vehicle_price
vehicle_price[ford]=7777
vehicle_price[toyota]=8888

vehicle_type=toyota
echo "${vehicle_price[$vehicle_type]}"
# gives
8888