‘whence’ is POSIX-reserved even in shells that don't implement it¹. (‘what’ is also in POSIX². And ‘who’ is on first³.) ¹ https://pubs.opengroup.org/onlinepubs

‘whence’ is POSIX-reserved even in shells that don't implement it¹. (‘what’ is also in POSIX². And ‘who’ is on first³.) ¹ https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_01_01 https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V... ² https://pubs.opengroup.org/onlinepubs/9699919799/idx/utilities.html https://pubs.opengroup.org/onlinepubs/9699919799/idx/utiliti... ³ https://youtu.be/kTcRRaXV-fg https://youtu.be/kTcRRaXV-fg