bash Version Differences in Mac OS X

Beware of differences in Mac OS shell commands executed by /bin/bash and /bin/sh.

These are not the same shell, despite the version output (example on Mac OS High Sierra). The version output is identical as shown below:

>/bin/sh --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin17)
Copyright (C) 2007 Free Software Foundation, Inc.
>/bin/bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin17)

Yet, the behaviour of these two binaries differs, for example in the echo command:

sh-3.2$ echo -n "test"
-n test
bash-3.2$ echo -n "test"

Note that echo in /bin/sh does not recognize “-n” and simply outputs the string, while /bin/bash recognizes the switch to mean omit newline.