You can write scripts in the semantics-preserving common subset of POSIX sh and bash, which is not quite, but close to exactly POSIX sh.
It's a widely-touted meme that scripting is more easily done in a general-purpose language than in a shell, but this is mostly true of the (common!) category of tasks which use the shell to launch sed &c. to perform string processing which is built-in in general-purpose languages. It's comparatively hard (i.e. verbose and error-prone) to replace a shell language with a general-purpose language in its core competence, viz. launching processes, muxing I/O, and coordinating parallel processing.
It's a widely-touted meme that scripting is more easily done in a general-purpose language than in a shell, but this is mostly true of the (common!) category of tasks which use the shell to launch sed &c. to perform string processing which is built-in in general-purpose languages. It's comparatively hard (i.e. verbose and error-prone) to replace a shell language with a general-purpose language in its core competence, viz. launching processes, muxing I/O, and coordinating parallel processing.