How to expand shell variables in a text file?

Question

Consider a ASCII text file (lets say it contains code of a non-shell scripting language):

Text_File.msh:

spool on to \'$LOG_FILE_PATH/lo         


        

Answer 1

If you want it in one line (I'm not a bash expert so there may be caveats to this but it works everywhere I've tried it):

when test.txt contains

${line1}
${line2}

then:

>line1=fark
>line2=fork
>value=$(eval "echo \"$(cat test.txt)\"")
>echo "$value"
line1 says fark
line2 says fork

Obviously if you just want to print it you can take out the extra value=$() and echo "$value".