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larsks
Asked: 2015-01-20 06:03:22 +0800 CST

How can I introspect the "shared subtree" mount flags for a particular mount?

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Under Linux, the shared subtree flags control how a mountpoint is shared with parent and child mount namespaces. These flags include MS_SHARED, MS_PRIVATE, and MS_SLAVE. How can one see which of these flags are set on a particular mountpoint?

These flags don't show up in the output of mount or in /proc/mounts.

linux

1 Answers

  1. Best Answer

    Check /proc/self/mountinfo. For instance, in one of my systemd-based Ubuntu VMs / is shared (systemd enforces it at boot time):

    $ cat /proc/self/mountinfo | grep ' / / '
22 0 8:1 / / rw,relatime shared:1 - ext4 /dev/disk/by-uuid/e176bae0-84a5-4bd2-b968-e809e902488c rw,data=ordered
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