Just for the fun of it results on a few UNIX versions
Intel - SCO UNIX 3.2V4.2
/bin/true: empty file
/bin/false: contains "exit 255"
file $(which true) $(which false)
Alpha - Digital Unix 4.0G
/usr/bin/true: COFF format alpha dynamically linked, demand paged
executable or object module stripped - version 3.11-10
/usr/bin/false: COFF format alpha dynamically linked, demand paged
executable or object module stripped - version 3.11-10
Alpha - Tru64 V5.1B
/usr/bin/true: COFF format alpha dynamically linked, demand paged
executable or object module stripped - version 3.13-14
/usr/bin/false: COFF format alpha dynamically linked, demand paged
executable or object module stripped - version 3.13-14
Itanium - HP-UX 11i B.11.23 & HP-UX 11i B.11.31
/sbin/true: ELF-32 executable object file - IA64
/sbin/false: ELF-32 executable object file - IA64