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In the USB storage section:

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Describe how to make USB devices mountable as a normal user.

PR:		docs/106148
Submitted by:	Roland Smith <rsmith@xs4all.nl>
With some help from:	ceri@
This commit is contained in:
Marc Fonvieille 2006-12-07 11:47:36 +00:00
parent 73210a7569
commit dc1f80fd35
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=29204
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en_US.ISO8859-1/books/handbook/disks/chapter.sgml
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@ -809,6 +809,63 @@ da0: 126MB (258048 512 byte sectors: 64H 32S/T 126C)</screen>
to format and create partitions on the USB drive if
needed.</para>
<para>To make this device mountable as a normal user, certain
steps have to be taken. First, the devices that are created
when a USB storage device is connected need to be accessible
by the user. A solution is to make all users of these devices
a member of the <groupname>operator</groupname> group. This
is done with &man.pw.8;. Second, when the devices are
created, the <groupname>operator</groupname> group should be
able to read and write them. This is accomplished by adding a
line for these devices to
<filename>/etc/devfs.rules</filename>:</para>
<programlisting>add path 'da*' mode 0660 group operator</programlisting>
<note>
<para>If there already are SCSI disks in the system, it must
be done a bit different. E.g., if the system already
contains disks <devicename>da0</devicename> through
<devicename>da2</devicename> attached to the system, change
the line as follows:</para>
<programlisting>add path 'da[3-9]*' mode 0660 group operator</programlisting>
<para>This will exclude the already existing disks from
belonging to the <groupname>operator</groupname>
group.</para>
</note>
<para>Next, the kernel has to be configured to allow regular
users to mount file systems. The easiest way is to add the
following line to
<filename>/etc/sysctl.conf</filename>:</para>
<programlisting>vfs.usermount="1"</programlisting>
<para>Note that this only takes effect after the next reboot.
Alternatively, one can also use &man.sysctl.8; to set this
variable.</para>
<para>The final step is to create a directory where the file
system is to be mounted. This directory needs to be owned by
the user that is to mount the file system. One way to do that
is for <username>root</username> to create a subdirectory
owned by that user as
<filename>/mnt/<replaceable>$USER</replaceable></filename>
(replace <replaceable>$USER</replaceable> by the login name of
the actual user):</para>
<screen>&prompt.root; <userinput>mkdir /mnt/$USER</userinput>
&prompt.root; <userinput>chown <replaceable>$USER</replaceable>:<replaceable>$USER</replaceable> /mnt/<replaceable>$USER</replaceable></userinput></screen>
<para>Suppose a USB thumbdrive is plugged in, and a device
<filename>/dev/da0s1</filename> appears. Since these devices
usually come preformatted with a FAT file system, one can
mount them like this:</para>
<screen>&prompt.user; <userinput>mount_msdosfs -m 644 -M 755 /dev/da0s1 /mnt/<replaceable>$USER</replaceable></userinput></screen>
<para>If you unplug the device (the disk must be unmounted
before), you should see, in the system message buffer,
something like the following:</para>