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=head1 名前
guestunmount - Unmount a guestmounted filesystem
=head1 書式
guestunmount mountpoint
guestunmount --fd=<FD> mountpoint
=head1 説明
guestunmount is a utility to clean up mounted filesystems automatically. L<guestmount(1)> mounts filesystems using libguestfs. This program unmounts the filesystem when a program or script has finished with it.
guestunmount is a wrapper around the FUSE L<fusermount(1)> program, which must exist on the current C<PATH>.
There are two ways to use guestunmount. When called as:
guestunmount mountpoint
it unmounts C<mountpoint> immediately.
When called as:
guestunmount --fd=FD mountpoint
it waits until the pipe C<FD> is closed. This can be used to monitor another process and clean up its mountpoint when that process exits, as described below.
=head2 FROM PROGRAMS
You can just call C<guestunmount mountpoint> from the program, but a more sophisticated way to use guestunmount is to have it monitor your program so it can clean up the mount point if your program exits unexpectedly.
In the program, create a pipe (eg. by calling L<pipe(2)>). Let C<FD> be the file descriptor number of the read side of the pipe (ie. C<pipefd[0]>).
After mounting the filesystem with L<guestmount(1)> (on C<mountpoint>), fork and run guestunmount like this:
guestunmount --fd=FD mountpoint
Close the read side of the pipe in the parent process.
Now, when the write side of the pipe (ie. C<pipefd[1]>) is closed for any reason, either explicitly or because the parent process exits, guestunmount notices and unmounts the mountpoint.
If your operating system supports it, you should set the C<FD_CLOEXEC> flag on the write side of the pipe. This is so that other child processes don't inherit the file descriptor and keep it open.
Guestunmount never daemonizes itself.
=head2 FROM SHELL SCRIPTS
Since bash doesn't provide a way to create an unnamed pipe, use a trap to call guestunmount on exit like this:
trap "guestunmount mountpoint" EXIT INT QUIT TERM
=head1 オプション
=over 4
=item B<--fd=FD>
Specify the pipe file descriptor to monitor, and delay cleanup until that pipe is closed.
=item B<--help>
簡単なヘルプを表示して、終了します。
=item B<-q>
=item B<--quiet>
Don’t display error messages from fusermount. The return status is still set (see L</EXIT STATUS> below).
=item B<--no-retry>
=item B<--retry=N>
By default, guestunmount will retry the fusermount operation up to S<5 times> (that is, it will run it up to S<6 times> = S<1 try> + S<5 retries>).
Use I<--no-retry> to make guestunmount run fusermount only once.
Use I<--retry=N> to make guestunmount retry C<N> times instead of 5.
guestunmount performs an exponential back-off between retries, waiting S<1 second>, S<2 seconds>, S<4 seconds>, etc before each retry.
=item B<-V>
=item B<--version>
プログラムのバージョンを表示して、終了します。
=back
=head1 環境変数
=over 4
=item C<PATH>
The L<fusermount(1)> program (supplied by FUSE) must be available on the current C<PATH>.
=back
=head1 終了ステータス
This program returns 0 if successful, or one of the following error codes:
=over 4
=item C<1>
Program error, eg. could not allocate memory, could not run fusermount. See the error message printed for more information.
=item C<2>
The mount point could not be unmounted even after retrying. See the error message printed for the underlying fusermount error.
=item C<3>
The mount point is not mounted.
=back
=head1 関連項目
L<guestmount(1)>, L<fusermount(1)>, L<pipe(2)>, L<guestfs(3)/MOUNT LOCAL>, L<http://libguestfs.org/>, L<http://fuse.sf.net/>.
=head1 著者
Richard W.M. Jones (C<rjones at redhat dot com>)
=head1 COPYRIGHT
Copyright (C) 2013 Red Hat Inc.
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