Maximum number of users on Linux

Question

What is the maximum number of users accounts I can have on Linux?

score 19 · Accepted Answer · answered Nov 12 '10 at 13:07

19

65.000 for 2.4 kernels, and 4 billion for 2.6 kernels.

answered Nov 12 '10 at 13:07

5

When are they gonna fix that? What if I want to make one account for every person in the world? – Johanna Larsson Nov 12 '10 at 13:31
Well, doesn't 64-bit linux support 2^128 users? – LawrenceC Nov 12 '10 at 13:47
5

Fun fact: assuming an the average entry in /etc/passwd is 75 bytes, 4 billion users would give you an /etc/passwd that's just a shade under 300GB. :-) – ThatGraemeGuy Nov 12 '10 at 14:17
2

@shintoist: Because things are made based on what's probable, not what's possible. It's possible that you would want to create a user account in a single Linux system for every person in the world, but it's not probable that you'd actually do that. – joeqwerty Nov 12 '10 at 14:39
1

@joeqwert Yes, because I was being serious... – Johanna Larsson Nov 12 '10 at 14:48
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Do you have any source of these numbers? – Fabian Jakobs Nov 14 '10 at 21:03
@Graeme. Haha. Of course you don't necessarily need to use `passwd` and `nsswitch compat`. – poolie Nov 19 '10 at 06:00
Don’t you mean 6,5536 (2¹⁶) or 4,294,967,296 (2³²)? (When including root (0) and everything below 1000.) 65000 is a very unnatural number for computers. – Evi1M4chine Jun 19 '22 at 11:21
@ThatGraemeGuy: Usually, use uses things like LDAP/Kerberos for these situations. SQL-database-backed probably. – Evi1M4chine Jun 19 '22 at 11:22

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