为什么不“挂载”使用手册页中列出的所有默认选项？

Question

I'm trying to mount the partition /dev/sda4 like this:

sudo mount /dev/sda4

My /etc/fstab has this line:

/dev/sda4 /home/lv/Media ext4 defaults 0 2

But still when I use mount I get this:

/dev/sda4 on /home/lv/Media type ext4 (rw)

I read defaults should be equal to rw, suid, dev, exec, auto, nouser, async, and relatime. What's the deal with this?

Answer 1

From fstab(5) :

defaults

use default options: rw, suid, dev, exec, auto, nouser, and async.

I believe, all these options are default behaviour and thus not shown explicitly (one exception is rw ). If nosuid is not given, mount defaults to suid ; if nodev is not given, mount defaults to dev , and so on.

For example, noexec option is shown:

$ mount /dev/sda1 foo -o noexec
$ ./foo/bin/date 
zsh: permission denied: ./foo/bin/date
$ mount | grep foo
/dev/sda1 on /root/foo type ext4 (rw,noexec)

But exec option is not:

$ mount /dev/sda1 foo -o exec  
$ ./foo/bin/date             
Tue Jul 28 08:58:36 MSK 2015
$ mount | grep foo           
/dev/sda1 on /root/foo type ext4 (rw)