PAM_USERTYPE(8)

💖 PAM_USERTYPE 💖

okay bestie, welcome to pam_usertype — it's the Linux-PAM module that does a lil vibe check on what kind of account you're dealing with 🕵️♀️ no cap.

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✨ NAME ✨

pam_usertype — check if the authenticated user is a system or regular account 👑 (yes that's the whole job, and she does it flawlessly)

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🌸 SYNOPSIS 🌸

pam_usertype.so [flag...] {condition}

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🦋 DESCRIPTION 🦋

so like, pam_usertype.so is literally designed to succeed or fail authentication based on the type of the account of the authenticated user. and how does it figure out the type?? with a lil help from the SYS_UID_MAX settings in /etc/login.defs 💅 iykyk.

one super iconic use case: choosing whether to load other modules based on this test. like, gatekeeping but make it productive ✨

⚠️ bestie listen — the module should be given only one condition as module argument. that's it. one. Authentication will succeed only if the condition is met. periodt.

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💅 OPTIONS 💅

the following flags are supported, and yes they're both lowkey essential:

• use_uid — evaluate conditions using the account of the user whose UID the application is running under, instead of the user being authenticated. it's giving "who am I really" energy 🙈
• audit — log unknown users to the system log. snitch mode: activated 📝

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🎀 Available conditions are:

• issystem — succeed if the user is a system user 💻
• isregular — succeed if the user is a regular user 🧚

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🌈 MODULE TYPES PROVIDED 🌈

all module types are provided — account, auth, password and session. she's versatile. she contains multitudes. main character energy fr fr 👑

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🔥 RETURN VALUES 🔥

here's the receipts, bestie:

• PAM_SUCCESS — the condition was true. slay!! ✅
• PAM_BUF_ERR — memory buffer error 😭
• PAM_CONV_ERR — the conversation method supplied by the application failed to obtain the username 🗣️❌
• PAM_INCOMPLETE — the conversation method supplied by the application returned PAM_CONV_AGAIN 🌀
• PAM_AUTH_ERR — the condition was false. not today 💀
• PAM_SERVICE_ERR — a service error occurred, or the arguments can't be parsed correctly 🫠
• PAM_USER_UNKNOWN — user was not found. who?? never heard of her 🙈

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🍓 EXAMPLES 🍓

skip the remaining modules if the user is a system user — the classic:

account sufficient pam_usertype.so issystem

like, if you're a system user you're done here, no further modules, bye bye 👋✨

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💜 SEE ALSO 💜

login.defs(5), pam(8) — go read those too, bestie, they're the supporting cast 🫶

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🌸 AUTHOR 🌸

Pavel Březina <pbrezina@redhat.com> — the icon, the legend, the moment ⭐

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and that's the whole page!! this one came from the Linux-PAM manual, dated 09/27/2026, and it's literally called PAM_USERTYPE(8). mwah 💋 go forth and type-check your users 🌈💖