Ubuntu Manpage: restore - restore files or file systems from backups made with dump

NAME

       restore - restore files or file systems from backups made with dump

SYNOPSIS

       restore  -C  [-cdHklMqvVy] [-b blocksize] [-D filesystem] [-f file] [-F script] [-L limit]
       [-s fileno] [-T directory]

       restore -i [-acdhHklmMNoquvVy] [-A file] [-b blocksize] [-f file] [-F  script]  [-Q  file]
       [-s fileno] [-T directory]

       restore  -P  file  [-acdhHklmMNquvVy] [-b blocksize] [-f file] [-F script] [-s fileno] [-T
       directory] [-X filelist] [ file ... ]

       restore -R [-cdHklMNquvVy] [-b blocksize] [-f file] [-F script] [-s fileno] [-T directory]

       restore -r [-cdHklMNquvVy] [-b blocksize] [-f file] [-F script] [-s fileno] [-T directory]

       restore -t [-cdhHklMNquvV0y] [-A file] [-b blocksize] [-f file] [-F script] [-Q file]  [-s
       fileno] [-T directory] [-X filelist] [ file ... ]

       restore  -x  [-adchHklmMNqouvVy]  [-A file] [-b blocksize] [-f file] [-F script] [-Q file]
       [-s fileno] [-T directory] [-X filelist] [ file ... ]

DESCRIPTION

The restore command performs the inverse function of dump(8). A full backup of a file
system may be restored and subsequent incremental backups layered on top of it. Single
files and directory subtrees may be restored from full or partial backups. Restore works
across a network; to do this see the -f flag described below. Other arguments to the
command are file or directory names specifying the files that are to be restored. Unless
the -h flag is specified (see below), the appearance of a directory name refers to the
files and (recursively) subdirectories of that directory.

Exactly one of the following flags is required:

-C This mode allows comparison of files from a dump. Restore reads the backup and
compares its contents with files present on the disk. It first changes its working
directory to the root of the filesystem that was dumped and compares the tape with
the files in its new current directory. See also the -L flag described below.

-i This mode allows interactive restoration of files from a dump. After reading in the
directory information from the dump, restore provides a shell like interface that
allows the user to move around the directory tree selecting files to be extracted.
The available commands are given below; for those commands that require an
argument, the default is the current directory.

add [arg]
The current directory or specified argument is added to the list of files to
be extracted. If a directory is specified, then it and all its descendants
are added to the extraction list (unless the -h flag is specified on the
command line). Files that are on the extraction list are prepended with a
“*” when they are listed by ls.

cd arg Change the current working directory to the specified argument.

delete [arg]
The current directory or specified argument is deleted from the list of
files to be extracted. If a directory is specified, then it and all its
descendants are deleted from the extraction list (unless the -h flag is
specified on the command line). The most expedient way to extract most of
the files from a directory is to add the directory to the extraction list
and then delete those files that are not needed.

extract
All files on the extraction list are extracted from the dump. Restore will
ask which volume the user wishes to mount. The fastest way to extract a few
files is to start with the last volume and work towards the first volume.

help List a summary of the available commands.

ls [arg]
List the current or specified directory. Entries that are directories are
appended with a “/”. Entries that have been marked for extraction are
prepended with a “*”. If the verbose flag is set, the inode number of each
entry is also listed.

pwd Print the full pathname of the current working directory.

quit Restore immediately exits, even if the extraction list is not empty.

setmodes
All directories that have been added to the extraction list have their
owner, modes, and times set; nothing is extracted from the dump. This is
useful for cleaning up after a restore has been prematurely aborted.

verbose
The sense of the -v flag is toggled. When set, the verbose flag causes the
ls command to list the inode numbers of all entries. It also causes restore
to print out information about each file as it is extracted.

-P file
Restore creates a new Quick File Access file file from an existing dump file
without restoring its contents.

-R Restore requests a particular tape of a multi-volume set on which to restart a full
restore (see the -r flag below). This is useful if the restore has been
interrupted.

-r Restore (rebuild) a file system. The target file system should be made pristine
with mke2fs(8), mounted, and the user cd'd into the pristine file system before
starting the restoration of the initial level 0 backup. If the level 0 restores
successfully, the -r flag may be used to restore any necessary incremental backups
on top of the level 0. The -r flag precludes an interactive file extraction and can
be detrimental to one's health (not to mention the disk) if not used carefully. An
example:

mke2fs /dev/sda1

mount /dev/sda1 /mnt

cd /mnt

restore rf /dev/st0

Note that restore leaves a file restoresymtable in the root directory to pass
information between incremental restore passes. This file should be removed when
the last incremental has been restored.

Restore, in conjunction with mke2fs(8) and dump(8), may be used to modify file
system parameters such as size or block size.

-t The names of the specified files are listed if they occur on the backup. If no file
argument is given, the root directory is listed, which results in the entire
content of the backup being listed, unless the -h flag has been specified. Note
that the -t flag replaces the function of the old dumpdir(8) program. See also the
-X option below. If the -0 flag is used, the output separator is the null
character (instead of the newline character).

-x The named files are read from the given media. If a named file matches a directory
whose contents are on the backup and the -h flag is not specified, the directory is
recursively extracted. The owner, modification time, and mode are restored (if
possible). If no file argument is given, the root directory is extracted, which
results in the entire content of the backup being extracted, unless the -h flag has
been specified. See also the -X option below.

OPTIONS

The following additional options may be specified:

-a In -i or -x mode, restore does ask the user for the volume number on which the
files to be extracted are supposed to be (in order to minimise the time by reading
only the interesting volumes). The -a option disables this behaviour and reads all
the volumes starting with 1. This option is useful when the operator does not know
on which volume the files to be extracted are and/or when he prefers the longer
unattended mode rather than the shorter interactive mode.

-A archive_file
Read the table of contents from archive_file instead of the media. This option can
be used in combination with the -t, -i, or -x options, making it possible to check
whether files are on the media without having to mount the media.

-b blocksize
The number of kilobytes per dump record. If the -b option is not specified, restore
tries to determine the media block size dynamically.

-c Normally, restore will try to determine dynamically whether the dump was made from
an old (pre-4.4) or new format file system. The -c flag disables this check, and
only allows reading a dump in the old format.

-d The -d (debug) flag causes restore to print debug information.

-D filesystem
The -D flag allows the user to specify the filesystem name when using restore with
the -C option to check the backup.

-f file
Read the backup from file; file may be a special device file like /dev/st0 (a tape
drive), /dev/sda1 (a disk drive), an ordinary file, or - (the standard input). If
the name of the file is of the form host:file or user@host:file, restore reads from
the named file on the remote host using rmt(8).

-F script
Run script at the beginning of each tape. The device name and the current volume
number are passed on the command line. The script must return 0 if restore should
continue without asking the user to change the tape, 1 if restore should continue
but ask the user to change the tape. Any other exit code will cause restore to
abort. For security reasons, restore reverts back to the real user ID and the real
group ID before running the script.

-h Extract the actual directory, rather than the files that it references. This
prevents hierarchical restoration of complete subtrees from the dump.

-H hash_size
Use a hashtable having the specified number of entries for storing the directories
entries instead of a linked list. This hashtable will considerably speed up inode
lookups (visible especially in interactive mode when adding/removing files from the
restore list), but at the price of much more memory usage. The default value is 1,
meaning no hashtable is used.

-k Use Kerberos authentication when contacting the remote tape server. (Only available
if this options was enabled when restore was compiled.)

-l When doing remote restores, assume the remote file is a regular file (instead of a
tape device). If you're restoring a remote compressed file, you will need to
specify this option or restore will fail to access it correctly.

-L limit
The -L flag allows the user to specify a maximal number of miscompares when using
restore with the -C option to check the backup. If this limit is reached, restore
will abort with an error message. A value of 0 (the default value) disables the
check.

-m Extract by inode numbers rather than by file name. This is useful if only a few
files are being extracted, and one wants to avoid regenerating the complete
pathname to the file.

-M Enables the multi-volume feature (for reading dumps made using the -M option of
dump). The name specified with -f is treated as a prefix and restore tries to read
in sequence from <prefix>001, <prefix>002 etc.

-N The -N flag causes restore to perform a full execution as requested by one of -i,
-R, -r, t or x command without actually writing any file on disk.

-o The -o flag causes restore to automatically restore the current directory
permissions without asking the operator whether to do so in one of -i or -x modes.

-q The -q flag causes restore to abort immediately whenever operator attention is
required, without prompting in case of read errors, tape changes etc.

-Q file
Use the file file in order to read tape position as stored using the dump Quick
File Access mode, in one of -i, -x or -t mode.

It is recommended to set up the st driver to return logical tape positions rather
than physical before calling dump/restore with parameter -Q. Since not all tape
devices support physical tape positions those tape devices return an error during
dump/restore when the st driver is set to the default physical setting. Please see
the st(4) man page, option MTSETDRVBUFFER , or the mt(1) man page, on how to set
the driver to return logical tape positions.

Before calling restore with parameter -Q, always make sure the st driver is set to
return the same type of tape position used during the call to dump. Otherwise
restore may be confused.

This option can be used when restoring from local or remote tapes (see above) or
from local or remote files.

-s fileno
Read from the specified fileno on a multi-file tape. File numbering starts at 1.

-T directory
The -T flag allows the user to specify a directory to use for the storage of
temporary files. The default value is /tmp. This flag is most useful when
restoring files after having booted from a floppy. There might be little or no
space on the floppy filesystem, but another source of space might exist.

-u When creating certain types of files, restore may generate a warning diagnostic if
they already exist in the target directory. To prevent this, the -u (unlink) flag
causes restore to remove old entries before attempting to create new ones.

-v Normally restore does its work silently. The -v (verbose) flag causes it to type
the name of each file it treats preceded by its file type.

-0 (zero terminated) flag causes the output lines to be zero terminated, not line feed
terminated. This flag is recognized for -t (listing) only.

-V Enables reading multi-volume non-tape mediums like CDROMs.

-X filelist
Read list of files to be listed or extracted from the text file filelist in
addition to those specified on the command line. This can be used in conjunction
with the -t or -x commands. The file filelist should contain file names separated
by newlines. filelist may be an ordinary file or - (the standard input).

-y Do not ask the user whether to abort the restore in the event of an error. Always
try to skip over the bad block(s) and continue.

(The 4.3BSD option syntax is implemented for backward compatibility but is not documented
here.)

DIAGNOSTICS

Complains if it gets a read error. If y has been specified, or the user responds y,
restore will attempt to continue the restore.

If a backup was made using more than one tape volume, restore will notify the user when it
is time to mount the next volume. If the -x or -i flag has been specified, restore will
also ask which volume the user wishes to mount. The fastest way to extract a few files is
to start with the last volume, and work towards the first volume.

There are numerous consistency checks that can be listed by restore. Most checks are
self-explanatory or can “never happen”. Common errors are given below:

Converting to new file system format
A dump tape created from the old file system has been loaded. It is automatically
converted to the new file system format.

<filename>: not found on tape
The specified file name was listed in the tape directory, but was not found on the
tape. This is caused by tape read errors while looking for the file, and from using
a dump tape created on an active file system.

expected next file <inumber>, got <inumber>
A file that was not listed in the directory showed up. This can occur when using a
dump created on an active file system.

Incremental dump too low
When doing an incremental restore, a dump that was written before the previous
incremental dump, or that has too low an incremental level has been loaded.

Incremental dump too high
When doing an incremental restore, a dump that does not begin its coverage where
the previous incremental dump left off, or that has too high an incremental level
has been loaded.

Tape read error while restoring <filename>

Tape read error while skipping over inode <inumber>

Tape read error while trying to resynchronize
A tape (or other media) read error has occurred. If a file name is specified, its
contents are probably partially wrong. If an inode is being skipped or the tape is
trying to resynchronize, no extracted files have been corrupted, though files may
not be found on the tape.

resync restore, skipped <num> blocks
After a dump read error, restore may have to resynchronize itself. This message
lists the number of blocks that were skipped over.

EXIT STATUS

       Restore  exits with zero status on success. Tape errors are indicated with an exit code of
       1.

       When doing a comparison of files from a dump, an exit code of 2 indicates that some  files
       were modified or deleted since the dump was made.

ENVIRONMENT

       If the following environment variable exists it will be utilized by restore:

       TAPE   If  no  -f  option was specified, restore will use the device specified via TAPE as
              the  dump  device.   TAPE  may  be  of  the   form   tapename,   host:tapename   or
              user@host:tapename.

       TMPDIR The  directory  given  in  TMPDIR  will  be used instead of /tmp to store temporary
              files.

       RMT    The environment variable RMT will be used to determine the pathname of  the  remote
              rmt(8) program.

       RSH    Restore  uses  the  contents  of  this variable to determine the name of the remote
              shell command to use when doing a network restore (rsh, ssh etc.). If this variable
              is  not  set,  rcmd(3)  will  be  used,  but only root will be able to do a network
              restore.

FILES

       /dev/st0
              the default tape drive

       /tmp/rstdir*
              file containing directories on the tape

       /tmp/rstmode*
              owner, mode, and time stamps for directories

       ./restoresymtable
              information passed between incremental restores

BUGS

Restore can get confused when doing incremental restores from dumps that were made on
active file systems.

A level 0 dump must be done after a full restore. Because restore runs in user code, it
has no control over inode allocation; thus a full dump must be done to get a new set of
directories reflecting the new inode numbering, even though the content of the files is
unchanged.

The temporary files /tmp/rstdir* and /tmp/rstmode* are generated with a unique name based
on the date of the dump and the process ID (see mktemp(3)), except when -r or -R is used.
Because -R allows you to restart a -r operation that may have been interrupted, the
temporary files should be the same across different processes. In all other cases, the
files are unique because it is possible to have two different dumps started at the same
time, and separate operations shouldn't conflict with each other.

To do a network restore, you have to run restore as root or use a remote shell replacement
(see RSH variable). This is due to the previous security history of dump and restore. (
restore is written to be setuid root, but we are not certain all bugs are gone from the
code - run setuid at your own risk.)

At the end of restores in -i or -x modes (unless -o option is in use), restore will ask
the operator whether to set the permissions on the current directory. If the operator
confirms this action, the permissions on the directory from where restore was launched
will be replaced by the permissions on the dumped root inode. Although this behaviour is
not really a bug, it has proven itself to be confusing for many users, so it is
recommended to answer 'no', unless you're performing a full restore and you do want to
restore the permissions on '/'.

It should be underlined that because it runs in user code, restore , when run with the -C
option, sees the files as the kernel presents them, whereas dump sees all the files on a
given filesystem. In particular, this can cause some confusion when comparing a dumped
filesystem a part of which is hidden by a filesystem mounted on top of it.

AUTHOR

       The  dump/restore  backup  suite was ported to Linux's Second Extended File System by Remy
       Card <card@Linux.EU.Org>. He maintained the initial versions of  dump  (up  and  including
       0.4b4, released in January 1997).

       Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.

AVAILABILITY

       The dump/restore backup suite is available from <https://dump.sourceforge.io>

HISTORY

       The restore command appeared in 4.2BSD.