More specifically, it aims to be POSIX `sh`-compatible, which gives a large speed boost in many cases. There's a `checkbashisms` command in Debian's `devscript

More specifically, it aims to be POSIX `sh`-compatible, which gives a large speed boost in many cases. There's a `checkbashisms` command in Debian's `devscripts` package to ensure scripts will work correctly under both shells.