sed -i -r '/^[\s\t]*[#;]/d' <file>
sed -i -r '/^\s*$/d' <file>
For all files in the current folder:
find . -type f -exec sed -i -r '/^[\s\t]*[#;]/d' {} +
find . -type f -exec sed -i -r '/^\s*$/d' {} +
sed -i -r '/^[\s\t]*[#;]/d' <file>
sed -i -r '/^\s*$/d' <file>
For all files in the current folder:
find . -type f -exec sed -i -r '/^[\s\t]*[#;]/d' {} +
find . -type f -exec sed -i -r '/^\s*$/d' {} +