From 1bfba3b0be32306b078f5ee527b864e758b2c77b Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Fri, 26 Apr 2019 15:52:54 +0000 Subject: Make a single hpr. Full doc, first draft. --- doc/s6-linux-init-umountall.html | 61 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 doc/s6-linux-init-umountall.html (limited to 'doc/s6-linux-init-umountall.html') diff --git a/doc/s6-linux-init-umountall.html b/doc/s6-linux-init-umountall.html new file mode 100644 index 0000000..c2402fd --- /dev/null +++ b/doc/s6-linux-init-umountall.html @@ -0,0 +1,61 @@ + + + + + + s6-linux-init: the s6-linux-init-umountall program + + + + + + +

+ +

The `s6-linux-init-umountall` program

+ +

+ s6-linux-init-umountall unmounts all the filesystems. +

+ +

Interface

+ +

+     s6-linux-init-umountall
+

+ +

s6-linux-init-umountall unmounts all partitions according to /proc/mounts. +It processes /proc/mounts in the reverse order, starting with the most recently mounted +partition and ending with the root filesystem ("unmounting" the root filesystem means remounting +it read-only).
s6-linux-init-umountall does not touch /etc/mtab.
If a filesystem fails to unmount, a warning is printed to stderr, but +s6-linux-init-umountall still attempts to unmount all the other ones.

+ +

Notes

+ +

s6-linux-init-umountall is automatically called at the very end of the shutdown procedure, +in "stage 4", i.e. after a SIGKILL has been sent to all the processes on the system, and +right before the system reboots (or halts, or is powered off). By that point, there is +no possible process that could prevent real file systems from being unmounted.
It is likely that some filesystems will still fail to unmount, typically +/proc and /dev. That's okay: those are pseudo-filesystems, and +will not cause data loss or a fsck if the system shuts down while they are still mounted.
Distributions usually provide a umount command with a -a option +to unmount all filesystems. That command is usually bloated with historical artifacts +and relies on unsafe interfaces, so it was decided not to use it. The +s6-linux-utils package also +provides a s6-umount +command with a -a option, but adding a dependency to that package would be a +higher cost than simply reimplementing the specific functionality here.

+ + + -- cgit v1.3.1

The s6-linux-init-umountall program

Interface

Notes

The `s6-linux-init-umountall` program