Subsequent elements are parameters. The list must be
non-empty (ie. must contain a program name).
+The return value is anything printed to I<stdout> by
+the command.
+
+If the command returns a non-zero exit status, then
+this function returns an error message. The error message
+string is the content of I<stderr> from the command.
+
The C<$PATH> environment variable will contain at least
C</usr/bin> and C</bin>. If you require a program from
another location, you should provide the full path in the
all filesystems that are needed are mounted at the right
locations.
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
=head2 command-lines
command-lines 'arguments ...'
This is the same as C<command>, but splits the
result into a list of lines.
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
=head2 config
config qemuparam qemuvalue
C<value> can be NULL.
+=head2 cp
+
+ cp src dest
+
+This copies a file from C<src> to C<dest> where C<dest> is
+either a destination filename or destination directory.
+
+=head2 cp-a
+
+ cp-a src dest
+
+This copies a file or directory from C<src> to C<dest>
+recursively using the C<cp -a> command.
+
=head2 debug
debug subcmd 'extraargs ...'
to look at the file C<daemon/debug.c> in the libguestfs source
to find out what you can do.
+=head2 dmesg
+
+ dmesg
+
+This returns the kernel messages (C<dmesg> output) from
+the guest kernel. This is sometimes useful for extended
+debugging of problems.
+
+Another way to get the same information is to enable
+verbose messages with C<set-verbose> or by setting
+the environment variable C<LIBGUESTFS_DEBUG=1> before
+running the program.
+
=head2 download
download remotefilename (filename|-)
Use C<-> instead of a filename to read/write from stdin/stdout.
+=head2 drop-caches
+
+ drop-caches whattodrop
+
+This instructs the guest kernel to drop its page cache,
+and/or dentries and inode caches. The parameter C<whattodrop>
+tells the kernel what precisely to drop, see
+L<http://linux-mm.org/Drop_Caches>
+
+Setting C<whattodrop> to 3 should drop everything.
+
+This automatically calls L<sync(2)> before the operation,
+so that the maximum guest memory is freed.
+
+=head2 equal
+
+ equal file1 file2
+
+This compares the two files C<file1> and C<file2> and returns
+true if their content is exactly equal, or false otherwise.
+
+The external L<cmp(1)> program is used for the comparison.
+
=head2 exists
exists path
should have filesystem type C<fstype>.
The returned integer is the status. See L<fsck(8)> for the
-list of status codes from C<fsck>, and note that multiple
-status codes can be summed together.
+list of status codes from C<fsck>.
+
+Notes:
+
+=over 4
+
+=item *
+
+Multiple status codes can be summed together.
-It is entirely equivalent to running C<fsck -a -t fstype device>.
-Note that checking or repairing NTFS volumes is not supported
+=item *
+
+A non-zero return code can mean "success", for example if
+errors have been corrected on the filesystem.
+
+=item *
+
+Checking or repairing NTFS volumes is not supported
(by linux-ntfs).
+=back
+
+This command is entirely equivalent to running C<fsck -a -t fstype device>.
+
+=head2 get-append
+
+ get-append
+
+Return the additional kernel options which are added to the
+guest kernel command line.
+
+If C<NULL> then no options are added.
+
=head2 get-autosync
get-autosync
This returns the verbose messages flag.
+=head2 grub-install
+
+ grub-install root device
+
+This command installs GRUB (the Grand Unified Bootloader) on
+C<device>, with the root directory being C<root>.
+
+=head2 hexdump
+
+ hexdump path
+
+This runs C<hexdump -C> on the given C<path>. The result is
+the human-readable, canonical hex dump of the file.
+
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
=head2 is-busy
is-busy
mkfs fstype device
This creates a filesystem on C<device> (usually a partition
-of LVM logical volume). The filesystem type is C<fstype>, for
+or LVM logical volume). The filesystem type is C<fstype>, for
example C<ext3>.
=head2 mount
Some internal mounts are not shown.
+=head2 mv
+
+ mv src dest
+
+This moves a file from C<src> to C<dest> where C<dest> is
+either a destination filename or destination directory.
+
+=head2 ping-daemon
+
+ ping-daemon
+
+This is a test probe into the guestfs daemon running inside
+the qemu subprocess. Calling this function checks that the
+daemon responds to the ping message, without affecting the daemon
+or attached block device(s) in any other way.
+
=head2 pvcreate
pvcreate device
Remove the single directory C<path>.
+=head2 set-append | append
+
+ set-append append
+
+This function is used to add additional options to the
+guest kernel command line.
+
+The default is C<NULL> unless overridden by setting
+C<LIBGUESTFS_APPEND> environment variable.
+
+Setting C<append> to C<NULL> means I<no> additional options
+are passed (libguestfs always adds a few of its own).
+
=head2 set-autosync | autosync
set-autosync true|false
The default is C<$libdir/guestfs> unless overridden by setting
C<LIBGUESTFS_PATH> environment variable.
-The string C<path> is stashed in the libguestfs handle, so the caller
-must make sure it remains valid for the lifetime of the handle.
-
Setting C<path> to C<NULL> restores the default path.
=head2 set-qemu | qemu
You can also override this by setting the C<LIBGUESTFS_QEMU>
environment variable.
-The string C<qemu> is stashed in the libguestfs handle, so the caller
-must make sure it remains valid for the lifetime of the handle.
-
Setting C<qemu> to C<NULL> restores the default qemu binary.
=head2 set-verbose | verbose
This is the same as the C<statvfs(2)> system call.
+=head2 strings
+
+ strings path
+
+This runs the L<strings(1)> command on a file and returns
+the list of printable strings found.
+
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
+=head2 strings-e
+
+ strings-e encoding path
+
+This is like the C<strings> command, but allows you to
+specify the encoding.
+
+See the L<strings(1)> manpage for the full list of encodings.
+
+Commonly useful encodings are C<l> (lower case L) which will
+show strings inside Windows/x86 files.
+
+The returned strings are transcoded to UTF-8.
+
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
=head2 sync
sync
then the length is calculated using C<strlen> (so in this case
the content cannot contain embedded ASCII NULs).
+I<NB.> Owing to a bug, writing content containing ASCII NUL
+characters does I<not> work, even if the length is specified.
+We hope to resolve this bug in a future version. In the meantime
+use C<upload>.
+
Because of the message protocol, there is a transfer limit
of somewhere between 2MB and 4MB. To transfer large files you should use
FTP.
to securely wipe the device). It should be sufficient to remove
any partition tables, filesystem superblocks and so on.
+=head2 zerofree
+
+ zerofree device
+
+This runs the I<zerofree> program on C<device>. This program
+claims to zero unused inodes and disk blocks on an ext2/3
+filesystem, thus making it possible to compress the filesystem
+more effectively.
+
+You should B<not> run this program if the filesystem is
+mounted.
+
+It is possible that using this program can damage the filesystem
+or data on the filesystem.
+