The grammar of the POSIX shell (and derivatives) is not an LR-parsed language that can be implemented with yacc. It requires an advanced parser. There is an e

The grammar of the POSIX shell (and derivatives) is not an LR-parsed language that can be implemented with yacc. It requires an advanced parser. There is an effort with OCaml (and another with ADA) to create a formal and secure parser. They remark that dash is a handcrafted parser in C that cannot be formally assured. https://archive.fosdem.org/2018/schedule/event/code_parsing_posix_s_hell/ https://archive.fosdem.org/2018/schedule/event/code_parsing_... https://archive.fosdem.org/2019/schedule/event/ada_shell/ https://archive.fosdem.org/2019/schedule/event/ada_shell/