restore - restore files or file systems from backups made with
dump
restore -C [-cdHklMvVy] [-b blocksize]
[-D filesystem] [-f file] [-F
script] [-L limit] [-s fileno] [-T
directory]
restore -i [-acdhHklmMNouvVy] [-A
file] [-b blocksize] [-f file] [-F
script] [-Q file] [-s fileno] [-T
directory]
restore -P file [-acdhHklmMNuvVy] [-b
blocksize] [-f file] [-F script]
[-s fileno] [-T directory] [-X
filelist] [ file ... ]
restore -R [-cdHklMNuvVy] [-b
blocksize] [-f file] [-F script]
[-s fileno] [-T directory]
restore -r [-cdHklMNuvVy] [-b
blocksize] [-f file] [-F script]
[-s fileno] [-T directory]
restore -t [-cdhHklMNuvV0y] [-A file]
[-b blocksize] [-f file] [-F
script] [-Q file] [-s fileno] [-T
directory] [-X filelist] [ file ... ]
restore -x [-adchHklmMNouvVy] [-A
file] [-b blocksize] [-f file] [-F
script] [-Q file] [-s fileno] [-T
directory] [-X filelist] [ file ... ]
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.
- 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:
- 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.
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 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.)
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.
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.
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.
- /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
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.
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>.
The dump/restore backup suite is available from
<https://dump.sourceforge.io>
The restore command appeared in 4.2BSD.