Question

I have multiple variables in a shell script; i was trying to save some code duplication and wanted to do something like following

# variables
FLAG=SIM
SIM_ICR_KEY_VAL="http://www.example.com/simi/icr"
REAL_ICR_KEY_VAL="http://www.example.com/real"

Based on the FLAG value i want to access the correct variable (without using IF’s)
When i try this it echos the variable name & not the value itself.

 echo $(echo ${FLAG}_ICR_KEY_VAL)

On further note; i need to use these substitutions inline in a sed statememt:

sed "s!${ISTR_KEY}=.*!${ISTR_KEY}=${SIM_ISTR_KEY_VAL}!" > tmp.file

… i am not sure its possible or not, please suggest

Answer 1

Reflection can be achieved with the infamous eval:

eval thisvar=\$${FLAG}_INC_KEY_VAL;
echo "We are using $thisvar"

Whenever you find yourself dynamically synthesizing a variable name, though, you are probably Doing It Wrong. You should consider alternatives like arrays:

ICR_KEY_VAL[0]="http://www.example.com/simi/icr"
ICR_KEY_VAL[1]="http://www.example.com/real"

SIM=0

echo ${ICR_KEY_VAL[$SIM]}