More details and original code
Copy of makeThin.bash
Shebang line
Use only POSIX `read` options

Reference <http://pubs.opengroup.org/onlinepubs/009695399/utilities/read.html>.
Avoid "<() process substituion" bashism
Avoid non-POSIX `echo` parameters

Reference <http://pubs.opengroup.org/onlinepubs/009695399/utilities/echo.html>.