FEATURE_PRESENT(3)

📦 version 15.1, in freebsd 14.5, freebsd 15.1

💅 FEATURE_PRESENT(3) — like, the manual manual, bestie

okay so real talk: this is a page from the Library Functions Manual, and honestly? it's giving "short but iconic." let's get into it 🎀

✨ NAME ✨

feature_present — query presence of a kernel feature 👑

like, it asks the kernel "hey bestie, do you have this?" and the kernel answers. that's the whole vibe check.

🦋 LIBRARY 🦋

Standard C Library (libc, -lc) — yeah, the classic one. not some random third-party thing, we're in main character territory here.

🌸 SYNOPSIS 🌸

#include <unistd.h>

int
feature_present(const char *feature);

literally just include the header, and boom 💥 — feature_present is right there waiting for you. it takes one const char * called feature and hands you back an int. no cap.

💖 DESCRIPTION 💖

okay so the feature_present() function is literally the way for your application to figure out whether a specific kernel feature is present in the currently running kernel. like, the one that's running right now, no guessing, no vibes-only.

the feature argument specifies the name of the feature to check 🫶 that's it, that's the assignment.

the feature_present() function will return 1 if the specified feature is present — slay — otherwise it will return 0. and hmm, important one: if the feature_present() function is not able to determine the presence of feature due to an internal error, it will return 0 too 😭 so like, "nope" and "idk, something broke" both look the same from the outside. that's the lore, i don't make the rules.

🎀 RETURN VALUES 🎀

  • if feature is present → 1 is returned ✨
  • otherwise → 0 is returned

periodt. that's the whole return protocol, no notes 💅

🌈 SEE ALSO 🌈

go read those too, iykyk 📚

🧚 HISTORY 🧚

the feature_present() function first appeared in FreeBSD 8.0. a legend from day one, fr fr ⭐

quick reminder bestie: internal error → 0. don't read that as a confident "nope," okay? 🙈

and that's the page! this little gem came to you courtesy of Debian, dated January 8, 2008 — yeah, it's been iconic since '08 💜 mwah, go forth and feature-check responsibly 🫶

📦 where this page comes from