envsub

Substitute Environment variable definition in template file by real values of ENV

Examples of template variable definition:

 ${VARIABLE}            Value of $VARIABLE or empty if variable is not set.
 ${VARIABLE=default}    Value of $VARIABLE or "default" if variable is not set.
 ${VARIABLE-}           Value of $VARIABLE or skip whole line if variable is not set.

Usage

Print to console

$ envsub -i example.tpl

Save to file

$ envsub -i example.tpl > output.conf