pmount man page on Knoppix

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pmount(1)							     pmount(1)

NAME
       pmount - mount arbitrary hotpluggable devices as normal user

SYNOPSIS
       pmount [ options ] device

       pmount [ options ] device label

       pmount --lock [ options ] device pid

       pmount --unlock [ options ] device pid

       pmount

DESCRIPTION
       pmount  ("policy mount") is a wrapper around the standard mount program
       which permits normal users to mount removable devices without a	match‐
       ing /etc/fstab entry.

       pmount also supports encrypted devices which use dm-crypt and have LUKS
       metadata. If a LUKS-capable cryptsetup is installed, pmount will use it
       to  decrypt  the	 device	 first and mount the mapped unencrypted device
       instead.

       pmount is invoked like this:

       pmount device [ label ]

       This will mount device to a directory below /media  if  policy  is  met
       (see  below).  If label is given, the mount point will be /media/label,
       otherwise it will be /media/device.

       The   device   will   be	  mounted   with    the	   following	flags:
       async,atime,nodev,noexec,noauto,nosuid,user,rw

       Some applications like CD burners modify a raw device which must not be
       mounted while the burning process is in progress. To prevent  automatic
       mounting,  pmount  offers a locking mechanism: pmount --lock device pid
       will prevent the pmounting of device until it is unlocked  again	 using
       pmount  --unlock	 device	 pid. The process id pid assigns the lock to a
       particular process; this allows to lock a device by several processes.

       During mount, the list of locks is cleaned, i. e. all locks whose asso‐
       ciated  process does not exist any more are removed. This prevents for‐
       gotten indefinite locks from crashed programs.

       Running pmount without arguments prints the list of  mounted  removable
       devices, a bit in the fashion of mount (1).

       Please note that you can use labels and uuids as described in fstab (5)
       for devices present in /etc/fstab.  In this case, the device name  need
       to  match  exactly the corresponding entry in /etc/fstab, including the
       LABEL= or UUID= part.

       Important  note	for  Debian:  The  permission  to  execute  pmount  is
       restricted to members of the system group plugdev. Please add all desk‐
       top users who shall be able to use pmount to this group by executing

	      adduser user plugdev

       (as root).

POLICY
       The mount will succeed if all of the following conditions are met:

       · device is a block device in /dev/

       · device is not in /etc/fstab (if it is, pmount executes	 mount	device
	 as the calling user to handle this transparently). See below for more
	 details.

       · device is not already mounted according to /etc/mtab and /proc/mounts

       · if the mount point already exists, there is no device already mounted
	 at it and the directory is empty

       · device	  is   removable   (USB,   FireWire,   or   MMC	  device,   or
	 /sys/block/drive/removable is 1) or whitelisted in /etc/pmount.allow.

       · device is not locked

OPTIONS
       -r, --read-only
	      Force the device to be mounted read only. If neither -r  nor  -w
	      is specified, the kernel will choose an appropriate default.

       -w, --read-write
	      Force  the device to be mounted read/write. If neither -r nor -w
	      is specified, the kernel will choose an appropriate default.

       -s, --sync
	      Mount the device with the	 sync  option,	i.  e.	without	 write
	      caching.	Default is async (write-back). With this option, write
	      operations are much slower and due to the	 massive  increase  of
	      updates  of inode/FAT structures, flash devices may suffer heav‐
	      ily if you write large files. This option is intended to make it
	      safe to just rip out USB drives without proper unmounting.

       -A, --noatime
	      Mount the device with the noatime option. Default is atime.

       -e, --exec
	      Mount the device with the exec option. Default is noexec.

       -t filesystem, --type filesystem
	      Mount  as	 specified  file  system type. The file system type is
	      automatically determined if this option is not given. See at the
	      bottom for a list of currently supported filesystems.

       -c charset, --charset charset
	      Use given I/O character set (default: utf8 if called in an UTF-8
	      locale, otherwise mount  default).  This	corresponds  with  the
	      mount option iocharset (or nls for NTFS). This option is ignored
	      for file systems that do not support setting the	character  set
	      (see  mount  (8)	for details).  Important note: pmount will now
	      mount   VFAT    filesystems    with    iocharset=iso8859-1    as
	      iocharset=utf8  currently	 makes	the  filesystem case-sensitive
	      (which is pretty bad...).

       -u umask, --umask umask
	      Use specified umask instead of the default  one.	For  UDF,  the
	      default  is  '000', for VFAT and NTFS the default is '077'. This
	      value is ignored for file systems which do not  support  setting
	      an  umask. Note that you can use a value of 077 to forbid anyone
	      else to read/write the files, 027 to allow your  group  to  read
	      the  files  and  022 to allow anyone to read the files (but only
	      you can write).

       --dmask dmask

       --fmask fmask
	      Some filesystems (essentially VFAT and  HFS)  supports  separate
	      umasks (see the -u option just above) for directories and files,
	      to avoid the annoying effect of having all files executable. For
	      these  filesystems,  you	can specify separately the masks using
	      these options. By default, fmask is umask without all executable
	      permissions  and	dmask is umask.	 Most of the times, these set‐
	      tings should just do what you want, so there  should  be	seldom
	      any need for using directly the --fmask and --dmask options.

       -p file --passphrase file
	      If  the  device is encrypted (dm-crypt with LUKS metadata), read
	      the passphrase from specified file instead of prompting  at  the
	      terminal.

       -h, --help
	      Print a help message and exit successfully.

       -d, --debug
	      Enable verbose debug messages.

       -V, --version
	      Print the current version number and exit successfully.

FILES
       /etc/pmount.allow
	      List  of	devices	 (one  device per line) which are additionally
	      permitted for pmounting. Globs, such as /dev/sda[123]  are  per‐
	      mitted. See see glob (7) for a more complete syntax.

SEE ALSO
       pumount(1), mount(8)

SUPPORTED FILESYSTEMS
       For now, pmount supports the following filesystems: udf, iso9660, vfat,
       ntfs, hfsplus, hfs, ext3, ext2, ext4, reiserfs, reiser4, xfs,  jfs  and
       omfs.   They  are  tried	 sequentially  in  that	 exact	order when the
       filesystem is not specified.

       Additionally,  pmount  supports	the  filesystem	 types	ntfs-fuse  and
       ntfs-3g	to  mount  NTFS	 volumes  respectively	with  ntfsmount (1) or
       ntfs-3g (1). If the file /sbin/mount.ntfs-3g is found, then pmount will
       mount  NTFS  filestystems with type ntfs-3g rather than plain ntfs.  To
       disable this behavior, just specify -t ntfs  on	the  command-line,  as
       this happens only for autodetection.

MORE ABOUT FSTAB
       pmount  now  fully  resolve  all	 symlinks both in its input and in the
       /etc/fstab file, which  means  that  if	/dev/cdrom  is	a  symlink  to
       /dev/hdc	 and  you try to mount /dev/hdc directly, pmount will delegate
       this to mount(1).  This is a feature, and it  contrasts	with  previous
       unclear behavior of pmount about symlinks in /etc/fstab.

KNOWN ISSUES
       Though  we  believe  pmount is pretty much free from security problems,
       there are quite a few glitches that probably will never be fixed.

       · pmount needs to try several different	times  to  mount  to  get  the
	 filesystem  right in the end; it is vital that pmount does know which
	 precise filesystem to mount in order to give it the right options not
	 to  cause security holes. This is rather different from the behaviour
	 of mount with the -t auto options, which  can	have  a	 look  at  the
	 device	 it  is	 trying	 to mount and find out what its filesystem is.
	 pmount will never try to open a device and look at  it	 to  find  out
	 which	filesystem it is, as it might open quite a few security holes.
	 Moreover, the order in which the filesystems are tried	 are  what  we
	 could	call  the  most	 commonly used filesystems on removable media.
	 This order is unlikely to change as well. In particular,  that	 means
	 that  when you mount an ext3 filesystem using pmount, you might get a
	 lot of fs-related kernel error messages. Sorry !

       NOTE: Starting from version 0.9.17, pmount uses the same	 mechanism  as
       mount  (1)  to autodetect the filesystem type, so this kind of problems
       should not happen anymore.

AUTHOR
       pmount was originally developed	by  Martin  Pitt  <martin.pitt@canoni‐
       cal.com>.    It	 is   now   maintained	 by  Vincent  Fourmond	<four‐
       mond@debian.org>.

Martin Pitt			August 27, 2004			     pmount(1)
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