Bash Quick Start Guide

Understanding sh vs bash

If you have worked with shell script before, you might be wondering why we used #!/bin/bash as our shebang in all our examples, and not #!/bin/sh. Many users think that the /bin/sh and /bin/bash programs work the same way as shell script interpreters on every system. This is not true – there are important differences between the two.

The most important difference is that /bin/sh may not even be the same program as /bin/bash, and may therefore lack many of the programming features Bash adds that are not specified by the POSIX standard. Some GNU/Linux systems use bash as their /bin/sh implementation (Arch Linux, CentOS), but others do not (Debian GNU/Linux, Ubuntu).

When Bash is called as sh, it changes its behavior ...