[CentOS] Best practices for the maximal length of user names

Stephen Harris lists at spuddy.org
Sun Nov 14 11:13:14 EST 2010


On Sun, Nov 14, 2010 at 07:54:10AM -0800, Benjamin Franz wrote:
> CentOS5 supports 31 characters for user names (I tested it). 8 character 
> limits for user names was a holdover from some truly ancient Unix 
> systems and has been pretty much irrelevant to Linux for more than ten 
> years.

There are some minor side effects.

For example, from "man ps"
  If the length of the username is greater than the length of the display
  column, the numeric user ID is displayed instead.

On my 5.5 machine I have:
  haldaemon:x:68:68:HAL daemon:/:/sbin/nologin
and yet
  % ps aux | grep -w hald | grep -v root
  68        4389  0.0  0.1   6680  4640 ?        Ss   Oct24   0:06 hald
  68        4397  0.0  0.0   2108   828 ?        S    Oct24   0:00 hald-addon-acpi: listening on acpid socket /var/run/acpid.socket
  68        4401  0.0  0.0   2108   828 ?        S    Oct24   0:00 hald-addon-keyboard: listening on /dev/input/event0

Excluding minor artifacts like this, long user names work just fine.

-- 

rgds
Stephen


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