How to check if Linux user namespaces are supported by current OS kernel

Question

After doing some reading, I found that Linux user namespaces are generally supported in Linux versions >= 3.8. However, there's a possibility that user namespaces are disabled on a given OS, making the check for kernel versions unreliable. Is there a robust way to check if the current OS I'm using supports user namespaces and has it available to use?

Answer 1

There are two places you can check to see if your kernel supports user namespaces:

1. /boot/config-* . (find out which one you are actually using with uname -a )
2. /proc/config.gz .

In both files look for CONFIG_USER_NS . If it reads CONFIG_USER_NS=y you're golden. If not, well, you're about to compile a new kernel.

Answer 2

您可以检查当前进程' /proc/[pid]/ns/目录是否有一个名为user的文件：

ls /proc/self/ns

Answer 3

Provided you are running bash (you can check by running echo $0 , expected result is -bash ). Then you can run the following one liner:

if [[ `sudo cat /boot/config-$(uname -a | awk '{print $3}') |grep '^CONFIG_USER_NS'` == "CONFIG_USER_NS=y" ]]; then echo "You have support for User Namespaces"; else echo "Sorry, you don't have support for User Namespaces"; fi