Linux Kernel Module Cheat

27.4.5. sysconf

https://pubs.opengroup.org/onlinepubs/9699919799/functions/sysconf.html

Examples:

userland/posix/sysconf.c
userland/linux/sysconf.c showcases Linux extensions to POSIX

Note that this blows up on gem5 userland due to NPROCESSORS_ONLN however: https://gem5.atlassian.net/browse/GEM5-622

Get lots of info on the system configuration.

The constants can also be viewed accessed on my Ubuntu 18.04 host with:

getconf -a

getconf is also specified by POSIX at: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/getconf.html but not the -a option which shows all configurations.

Busybox 1.31.1 clearly states that getconf is not implemented however at docs/posix_conformance.txt:

POSIX Tools not supported:
  asa, at, batch, bc, c99, command, compress, csplit, ex, fc, file,
  gencat, getconf, iconv, join, link, locale, localedef, lp, m4,