Plan 9 from Bell Labs’s /usr/web/sources/contrib/quanstro/runetype-x/mkrunesize
#!/bin/rc rfork e awk ' BEGIN { x = 0 } $1 == "Runemax" { if(tolower($1) == "0xffff") print ENVIRON["rune16bit"] else if(tolower($1) == "0x10ffff") print ENVIRON["rune20bit"] } END { print ENVIRON["rune16bit"] }' </sys/include/libc.h