The inability to tune a fish was first documented in the original 4.2BSD man page for tunefs(8), https://www.tuhs.org/cgi-bin/utree.pl?file=4.2BSD/usr/man/man8

The inability to tune a fish was first documented in the original 4.2BSD man page for tunefs(8), https://www.tuhs.org/cgi-bin/utree.pl?file=4.2BSD/usr/man/man8/tunefs.8 https://www.tuhs.org/cgi-bin/utree.pl?file=4.2BSD/usr/man/ma... and is still present in most BSD-derived tunefs implementations, e.g., https://man.freebsd.org/cgi/man.cgi?query=tunefs&apropos=0&sektion=8&manpath=FreeBSD+13.2-RELEASE&arch=default&format=html https://man.freebsd.org/cgi/man.cgi?query=tunefs&apropos=0&s... AFAICT, this restriction does not apply to versions of tunefs provided by System V and its derivatives, e.g., https://docs.oracle.com/cd/E86824_01/html/E54764/tunefs-1m.html https://docs.oracle.com/cd/E86824_01/html/E54764/tunefs-1m.h... As with many things in UNIX, the ability to tune a fish is implementation-dependent, and testing is recommended before using it in production on any given platform.