kstrtobool(9)

💖 kstrtobool(9) — the kernel API manual, bestie edition 💖

okay so real talk, this one is a kstrtobool(9) situation and it's literally the most useful little gremlin in ./lib — it takes whatever chaos a user typed and turns it into a clean lil bool. no cap, it's giving "translator for the group chat". 🦋

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✨ SYNOPSIS ✨

int kstrtobool (const char *s , bool *res );

like, that's it. that's the whole vibe. 🎀

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🌸 ARGUMENTS 🌸

• s — the input string, aka whatever unhinged text the user handed you. the star of the show, main character energy fr.
• res — the result. this is where the answer lands, so bestie better be pointing somewhere real. 🫶

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕ — this routine returns 0 if and only if the first character is one of:

'EeYyTt1DdNnFf0'

...or it's [oO][NnFf] for "on" and "off". so yes, it's out here accepting y, Y, e, E, t, T, 1, d, D, n, N, f, F, 0, and the whole on/off duo — iconic, honestly. 💅

Otherwise it will return -EINVAL. no match, no mercy. 💀

and the value pointed to by res gets updated upon finding a match — so like, the moment it vibes with your input, it writes the result through the pointer. slay. ✨

ngl, notice it says first character — so it's checking the start of the string, not doing a deep read of the whole thing. don't come for me, that's just what the page says. 🙈

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👑 SEE ALSO 👑

• Kernel file ./lib/kstrtox.c
• _parse_integer_limit(9)
• kstrtoull(9)
• kstrtoll(9)
• kstrtouint(9)
• kstrtoint(9)
• kstrtoudec64(9)
• kstrtodec64(9)

the whole kstrto* friend group is there, go say hi. 🌈

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and that's the whole page, bestie — brought to you straight outta ./lib, dated October 2026, in the Kernel API Manual. mwah, go forth and convert those booleans 💋⭐🍓