Why * in /etc/security/limits.conf doesn't include root user?

问题

I'm running a java program as root on a linux machine. In order to increase the Max open files limitation, I added the following lines into /etc/security/limits.conf

*       soft    nofile  1000000
*       hard    nofile  1000000

However when I check the running program by cat /proc/<pid>/limits, it still tells me that the Max open files is 65536. Until I added another two lines into /etc/security/limits.conf, the Max open files could be changed to 1000000

root       soft    nofile  1000000
root       hard    nofile  1000000

I can see the comments from limits.conf, it says that

the wildcard *, for default entry.

So when I use * as default entry, doesn't it include root user? Why?

回答1:

Correct, it doesn't include root user. Looks like it has been done by design. From

man 5 limits.conf

NOTE: group and wildcard limits are not applied to the root user. To set a limit for the root user, this field must contain the literal username root.

来源：https://stackoverflow.com/questions/38991351/why-in-etc-security-limits-conf-doesnt-include-root-user