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

This solution is not elegant, but it works. Create a script call shell_expansion.sh:

echo 'cat <  temp.sh
cat "$1"                 >> temp.sh
echo 'END_OF_TEXT'       >> temp.sh
bash temp.sh >> "$2"
rm temp.sh

You can then invoke this script as followed:

bash shell_expansion.sh Text_File.msh Text_File_expanded.msh