SU(1)

💅 SU(1) — the su page, but make it cute

okay bestie, welcome to the General Commands Manual entry for su, aka the glow-up your terminal identity has been waiting for 👑

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✨ NAME ✨

su — substitute user identity

like, literally swap who you are. main character energy transfer. no cap.

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🦋 SYNOPSIS 🦋

su [-K | --no-kerberos] [-f] [-l | --full] [-m] [-i instance |
   --instance=instance] [-c command | --command=command] [login [shell
   arguments]]

she's giving "many flags, one girl." look at her. iconic.

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🌸 DESCRIPTION 🌸

so here's the tea ☕ — su will use Kerberos authentication, provided that an instance for the user who wants to change their effective UID is present in a file named .k5login in the target user id's home directory. that's the whole vibe check: no .k5login entry, no Kerberos moment. 🎀

there's a ✨special case✨ tho, and it's important so pay attention bestie: ‘root's’ ~/.k5login needs to contain an entry for:

‘user/⟨instance⟩@REALM’

for su to succeed (where ⟨instance⟩ is root unless you changed it with -i). yes queen, -i is the mood-setter here. 💅

now for the messy part 😭 — if there's either no entry for the current user in said file, or other problems happen (like missing host/hostname@REALM keys in the system's keytab, or the user just typing the wrong password), then su will fall back to traditional /etc/passwd authentication. it's giving backup plan. it's giving "we tried, we really did."

and when it's running on /etc/passwd authentication? su allows ‘root’ access only to members of the group wheel — OR to any user (as long as they know the ‘root’ password) if that group does not exist, or has no members. that's the rule, periodt. 🫶

the options are as follows:

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💖 OPTIONS 💖

• -K, --no-kerberos — don't use Kerberos. just… don't. skip it entirely. 🙈
• -f — don't read .cshrc. we're leaving that file on read, bestie. 💀
• -l, --full — simulate full login. the whole cinematic experience, not just a cameo. ✨
• -m — leave environment unmodified. touch nothing, change nothing, chaotic-neutral behavior. 🧚
• *-i *instance, --instance=instance — root instance to use. this is the one that matters for that special case up there. 👑
• *-c *command, --command=command — command to execute. tell her what to do and she'll do it. ⭐

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🌈 SEE ALSO 🌈

ngl, there isn't a SEE ALSO section on this one — she's a standalone queen, she doesn't need to name-drop other pages. 🎀

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⚠️ lowkey a heads-up: the Kerberos-to-/etc/passwd fallback and the wheel-group-only root access are real security behavior, not vibes. don't sleep on them. 😭

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and that's the whole page, bestie!! this one came from HEIMDAL, dated January 12, 2006 — yeah she's vintage, she's an elder icon, and she still ate. mwah 💋💖