what is the technology / programming language used by bitnami to develop ui based installer for linux which has .sh / .run extention

Binami has provided a UI for installing webstack in linux - what is the technology / programming language used to develop such ui based installer for linux.

Note : Python GUI, Java can be user but their innstaller is a .sh or .run file ?

so they didnt use python / java. then what is the language used.