Both the musl and GNU C libraries have a TTYDEF_OFLAG macro in a <sys/ttydefaults.h> header. It sets XTABS on, like it is still the 1960s. No GNU or musl programs that I have laid my hands on use this macro. The 'sane' setting to the stty utilities from GNU Core Utilities and BusyBox, and various programs that do an equivalent, all explicitly have their own default setting value and do not use these macros. On the BSDs, XTABS was taken out of this macro some time between 386BSD and 1994, and *their* sttys still use the macro to this day, sometimes indirectly via cfmakesane(). Sanity everywhere is letting these new-fangled 1970s terminals that understand a TAB character, and even sometimes soft-settable tabstops, do their things … except in the #musl and GNU C libraries. #termios #Unix #ComputerTerminals