Ubuntu only guest Session login (first-time deep feeling of the power of file permissions)

In order to test the Docker Mount permissions, the host's/etc/passwd file mounted to the virtual machine, into the virtual machine to see if I can directly to the host files on the operation, the/etc/passwd deleted the last ten lines ... Results the host on the/etc/passwd also changed, so you sudo function can not be used at all .... , fuck!

Fortunately, in the online search, using the/etc/passwd file system is a backup!!! cp/etc/passwd-/etc/passwd can, sure enough sudo can use.

But the more horrible problem arose, one day I restarted the system, found that the Ubuntu Gnome login interface, can only be logged in the guest session, press the interface after the screen can not see .... Tried a lot of ways are not, Baidu has some way to say is my own account uid, GID replaced by 0 ... Why the use of Baidu ...

Today suddenly an epiphany, is not the/etc/passwd authority problem in trouble!!! See the/etc/passwd of their own machine permissions is 600, but the normal machine, their other physical machine the same Ubuntu version, which unexpectedly is 644 .... , changed the power of my machine to 644, restart the machine, problem solving!

/etc/passwd

Ubuntu only guest Session login (first-time deep feeling of the power of file permissions)