Just because it is present, doesn't mean its the default or used internally by things that call shell scripts. For example... Not that long ago I started a new

Just because it is present, doesn't mean its the default or used internally by things that call shell scripts. For example... Not that long ago I started a new job where I took over as maintainer of a project with a fairly extensive Makefile, including targets for release. I cleaned it up some but missed a couple bashisms. The original author wrote it on a Mac, on which /bin/sh is bash, and used bashisms. I took over on Linux, which has /bin/sh as dash (POSIX). So while the author used it fine, it broke for me in subtle ways that I didn't notice until I made my first, broken release (error was in formatting of md5 signature file). The problem with bashisms is that people don't think through if their current use case is an appropriate one.