Provided by: e2undel_0.8-7_i386 bug

NAME

       e2undel — Undelete files on ext2 file systems interactively

SYNOPSIS

       e2undel-d device -s path  [-a]  [-t]

COPYRIGHT

       e2undel   (C)   Oliver   Diedrich  e2undel@sourceforge.net;  file  type
       functionality from the file(1) program, (C) (1987) Ian F. Darwin

DESCRIPTION

       Read this entire section before continuing! This section  contains  the
       usage description, for a more technical overview see the NOTES section.
       Please have a look at  the  SETUP  section  if  you  want  to  use  the
       ‘‘recover  deleted files by name’’ feature or if you want to give users
       other than root the ability to undelete.

       e2undel searches all inodes marked as deleted  on  a  file  system  and
       lists  them  assorted  by owner and time of deletion.  Additionally, it
       gives you the file size and tries to determine the file type in the way
       file(1)  does. If you did not just delete a whole bunch of files with a
       ’rm -r *’, this information should be helpful to find out which of  the
       deleted files you would like to recover.

       e2undel  does  not  actually undelete a file (i.e., does not manipulate
       ext2 internal structures like inode, block bitmap, and  inode  bitmap).
       Instead  it  recovers  the data of a deleted file and saves it in a new
       file.

       The following general rules should be  kept  in  mind  when  undeleting
       files:

          ·  The  device  from  which you want to recover deleted files should
             not be mounted in order to minimize the risk that other processes
             overwrite data of deleted files.

          ·  If  the  device  is mounted, the directory where you want to save
             the files should not reside on the same device. If it does, there
             is a chance the recently restored files overwrite deleted data.

          ·  The  sooner  as  you try to recover a deleted file the higher are
             chances that you will succeed.

OPTIONS

       e2undel accepts the following parameters:

        -d device
                 the file  system  where  to  look  for  deleted  files  (e.g.
                 /dev/hdb1  for the 1st partition on the 2nd IDE drive)

        -s path  the directory where recovered files are saved.

        -a       work on all files, not only on those listed in undel log file
                 (you need this if you don’t use the undel library)

       -t        try to determine type of deleted files without  names,  works
                 only with -a.

       -l        list  all  non-redundant  entries  in  the libundel log file,
                 sorted by file systems. Redundant  entries  can  exist  after
                 using  the  undel  library for some time if several files are
                 stored and deleted on the same inode. You can  use  the  tool
                 compactlog(8)  to  remove  these redundant entries if the log
                 file grows too heavy.

       Deleted files are displayed in a table user name by deletion  interval.
       The  deletion  intervals  are  less than 12 hours/48 hours/one week/one
       month/one year, with for example ‘‘one month’’ meaning ‘‘older than one
       week, but less than one month ago’’.  After selecting a user and a time
       interval, a list of matching files  is  displayed  with  inode  number,
       owner, deletion date, and name.  If you used the -a and the -t options,
       deleted files not found in the log file are displayed with  their  file
       type  instead of name, starting with a ’*’ (to have a visual difference
       between file names and file types).  Files printed in red are partially
       overwritten.   Enter the inode of a file to recover. Its data is stored
       in the directory given with the -s option. If the name of the  file  is
       known,  it  will  by used for the name of the recovered file, replacing
       all "/" in its path by "_".  If the name is not known, the name will be
       built from the inode number and -- if available -- its file type in the
       way ‘‘inode-xxx-file_type’’.

EXAMPLE

       An example:

       e2undel -d /dev/hdb2 -s /tmp

       tries to restore deleted files on /dev/hdb2 and  saves  them  in  /tmp.
       Deleted files with no name entry in the log file are ignored.

IMPORTANT

       As  soon as you realize you lost data, unmount the partition as soon as
       possible.

BUGS

          ·  missing pager functionality when displaying the list  of  deleted
             files, you need a terminal with a scrollback buffer

          ·  no direct way to recover a file by name

          ·  some  minor stuff, see BUGS (on Debian/GNU Linux system this file
             can be found in /usr/share/doc/e2undel).

SETUP

       Included in the e2undel package is the undel library. This  package  is
       currently  not build for Debian/GNU Linux.  This library, loaded by the
       $LD_PRELOAD mechanism,  hooks  into  the  system  calls  unlink(2)  and
       remove(3).   libundel  logs the device (like /dev/hdb7 etc.), the inode
       number, and the name of each file that is deleted by these system calls
       in   a   log   file   (/var/e2undel/e2undel  by  default).   With  this
       information, it is possible to  recover  deleted  files  by  name.   Of
       course,  e2undel  also  works  without  the  undel library (as outlined
       above), but you lose the functionality to recover deleted files by name
       if you don’t use libundel -- maybe the best part of this tool.

       First,  if  you  want  to  use  the  ‘‘recover  deleted files by name’’
       feature,   you   need   read   access   to    libundel’s    log    file
       /var/e2undel/e2undel  (and,  of  course,  the  undelete library must be
       installed). When following the installation instructions,  read  access
       to  the  libundel  log  is granted only for root. If ordinary users are
       allowed to use e2undel, you must change the rights of the libundel  log
       file  accordingly  (but  read the SECURITY section first !). Of course,
       you can only recover files by name that were deleted  after  installing
       the  undelete library. Other deleted files, however, are displayed when
       using the -a option.

       Second, you need read access  to  the  raw  file  system  device  (like
       /dev/hdb3  or /dev/sda9).  Most distributions grant read access to file
       system devices only to root and to a special group  (called  "disk"  on
       Red  Hat  systems,  for  example).   If  other users are allowed to use
       e2undel, you either have to change the access rights of the  device  or
       must  add  these  users  to the raw disk access group but first see the
       SECURITY section below.

SECURITY

       /var/log/e2undel: Each process on the system requires write  access  to
       this  file. You might consider this before using the undel library on a
       real multi user system.

       If you give all users read access to the log (needed to  use  e2undel),
       every  user  can  access each deleted file.  Access rights and owner of
       deleted files are ignored. This can be considered a problem in a  multi
       user environment. This also holds true if every user has read access to
       the file system device files. You can’t have the one without the other:
       If  a  user can recover deleted files on a file system, he can read all
       data on this file system. Even without e2undel, a simple

       dd /dev/xxx

       reads the complete file system.

NOTES

       If you delete a file stored on an ext2 file system,  its  data  is  not
       instantly lost. What happens is:

          ·  ext2  marks  the  file’s  data  blocks  as available in its block
             bitmap

          ·  ext2 marks the file’s inode as available in its inode bitmap

          ·  ext2 sets the deletion time in the file’s inode

          ·  ext2 invalidates the file’s name in the directory entry

       So,  the  file’s  data  is  not  actually  deleted  (but  it  might  be
       overwritten  in  the  future); and the crucial information in the inode
       (owner, access rights, size, data blocks occupied by the file and  some
       more)  is  not  touched.  If you know the inode number, you can recover
       the file by using Ted Ts’o’s debugfs(8) tool.

       What is lost however is the association between the file name  and  the
       inode:   You  can’t  restore  the  former  file  name  from  the  inode
       information.   To  recover  the  data  of  a  deleted  file,  you  must
       completely  rely on the information in the inode like file size, owner,
       deletion time, etc.  ext3 behaves different from ext2  in  one  regard:
       When  a  file is deleted, the information in the inode is also removed.
       Tools like e2undel  (or  Ted  T’so’s  debugfs(8))  that  rely  on  this
       information when undeleting files don’t work anymore.

       libundel  The undelete library uses standard mechanisms provided by the
                 glibc to hook into the  system  calls.  On  several  systems,
                 there  were no problems using the library. However, I did not
                 test the library on a heavily loaded server.

                 libundel  only  works  reliable  if  each  process  uses  the
                 library.   Problems  arise  from  programs started by scripts
                 that overwrite the $LD_PRELOAD variable (like  Netscape  does
                 on  some  distributions);  from processes that are started by
                 init scripts (i.e., before  $LD_PRELOAD  is  set);  by  using
                 su(1)  without a user name. The effect: Not all deleted files
                 are logged which might lead to confusion.

                 For example: A process using libundel deletes a  file:  inode
                 and  name  are  logged in /var/e2undel/e2undel. A new file is
                 stored on this inode and deleted by a process that  does  not
                 use the undel library.  e2undel now finds this inode deleted,
                 finds the (older) entry in the libundel  log,  and  concludes
                 that both belong together. When recovering the file, however,
                 the recent information in the deleted inode will be  restored
                 --  the data of the newer file is recovered under the name of
                 the older one. This can be somewhat confusing.

       e2undel   The program does not manipulate any internal ext2 structures,
                 requires only read access to the device it works on, and uses
                 Ted Ts’o’s ext2fs library for all ext2 low level  operations.
                 I  never  observed  any  damage to a file system treated with
                 e2undel.

       Files that were overwritten by mv(1) and friends can’t be recovered.

       Processes that create and delete a lot of temporary files can flood the
       log  file  with  senseless  information.  The  /tmp  directory might be
       concerned, but also other directories like the  user’s  Netscape  cache
       directories.  In  order  to  avoid these confusing entries, it might be
       useful to shift these directories on an own file system.

AUTHOR

       This  man  page  was  written  by  Helge  Kreutzmann   kreutzm@itp.uni-
       hannover.de  and  later  improved  by  Chris  Niekel   for  the  Debian
       GNU/Linux project but may be used by others.

SEE ALSO

       debugfs(8),  compactlog(8),  file(1),  /usr/share/doc/e2undel/recovery-
       howto.html,
        (link to URL http://e2undel.sourceforge.net/recovery-howto.html)

                                                                    e2undel(8)