NAME¶

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

SYNOPSIS¶

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 -Pfile[-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 ... ]

DESCRIPTION¶

Therestorecommand performs the inverse function ofdump(8).A full backup of a file system may be restored and subsequent incrementalbackups layered on top of it. Single files and directory subtrees may berestored from full or partial backups.Restoreworks across a network; to do this see the-fflag described below. Other arguments to the command are file or directorynames specifying the files that are to be restored. Unless the-hflag is specified (see below), the appearance of a directory name refers tothe 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.Restorereads the backup and compares its contents with files present on the disk. Itfirst changes its working directory to the root of the filesystem that wasdumped and compares the tape with the files in its new current directory. Seealso the-Lflag described below.

-i

This mode allows interactive restoration of files from a dump. After reading inthe directory information from the dump,restoreprovides a shell like interface that allows the user to move around thedirectory tree selecting files to be extracted. The available commands aregiven below; for those commands that require an argument, the default is thecurrent directory.

-P file

Restorecreates a new Quick File Access filefilefrom an existing dump file without restoring its contents.

-R

Restorerequests a particular tape of a multi-volume set on which to restart a fullrestore (see the-rflag below). This is useful if the restore has been interrupted.

-r

Restore (rebuild) a file system. The target file system should be made pristinewithmke2fs(8),mounted, and the usercd'dinto the pristine file system before starting the restoration of the initiallevel 0 backup. If the level 0 restores successfully, the-rflag may be used to restore any necessary incremental backups on top of thelevel 0. The-rflag precludes an interactive file extraction and can be detrimental to one'shealth (not to mention the disk) if not used carefully. An example:

Note thatrestoreleaves a filerestoresymtablein 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 withmke2fs(8)anddump(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 nofile argument is given, the root directory is listed, which results in theentire content of the backup being listed, unless the-hflag has been specified. Note that the-tflag replaces the function of the olddumpdir(8)program. See also the-Xoption below.If the-0flag 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 adirectory whose contents are on the backup and the-hflag is not specified, the directory is recursively extracted. The owner,modification time, and mode are restored (if possible). If no file argument isgiven, the root directory is extracted, which results in the entire content ofthe backup being extracted, unless the-hflag has been specified. See also the-Xoption below.

OPTIONS¶

The following additional options may be specified:

-a

In-ior-xmode,restoredoes ask the user for the volume number on which the files to be extracted aresupposed to be (in order to minimise the time by reading only the interestingvolumes). The-aoption disables this behaviour and reads all the volumes starting with 1. Thisoption is useful when the operator does not know on which volume the files tobe extracted are and/or when he prefers the longer unattended mode rather thanthe shorter interactive mode.

-A archive_file

Read the table of contents fromarchive_fileinstead of the media. This option can be used in combination with the-t,-i,or-xoptions, making it possible to check whether files are on the media withouthaving to mount the media.

-b blocksize

The number of kilobytes per dump record. If the-boption is not specified,restoretries to determine the media block size dynamically.

-c

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

-d

The-d(debug) flag causesrestoreto print debug information.

-D filesystem

The-Dflag allows the user to specify the filesystem name when usingrestorewith the-Coption to check the backup.

-f file

Read the backup fromfile;filemay 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 formhost:fileoruser@host:file,restorereads from the named file on the remote host usingrmt(8).

-F script

Run script at the beginning of each tape. The device name and the currentvolume number are passed on the command line. The script must return 0 ifrestoreshould continue without asking the user to change the tape, 1 ifrestoreshould continue but ask the user to change the tape. Any other exit code willcauserestoreto abort. For security reasons,restorereverts back to the real user ID and the real group ID before running thescript.

-h

Extract the actual directory, rather than the files that it references. Thisprevents hierarchical restoration of complete subtrees from the dump.

-H hash_size

Use a hashtable having the specified number of entries for storing thedirectories entries instead of a linked list. This hashtable willconsiderably speed up inode lookups (visible especially in interactivemode when adding/removing files from the restore list), but at theprice of much more memory usage. The default value is 1, meaning nohashtable is used.

-k

Use Kerberos authentication when contacting the remote tape server. (Onlyavailable if this options was enabled whenrestorewas compiled.)

-l

When doing remote restores, assume the remote file is a regular file (insteadof a tape device). If you're restoring a remote compressed file, you will needto specify this option orrestorewill fail to access it correctly.

-L limit

The-Lflag allows the user to specify a maximal number of miscompares when usingrestorewith the-Coption to check the backup. If this limit is reached,restorewill abort with an error message. A value of 0 (the default value) disablesthe check.

-m

Extract by inode numbers rather than by file name. This is useful if only a fewfiles are being extracted, and one wants to avoid regenerating the completepathname to the file.

-M

Enables the multi-volume feature (for reading dumps made using the-Moption of dump). The name specified with-fis treated as a prefix andrestoretries to read in sequence from<prefix>001, <prefix>002etc.

-N

The-Nflag causesrestoreto perform a full execution as requested by one of-i,-R,-r,torxcommand without actually writing any file on disk.

-o

The-oflag causesrestoreto automatically restore the current directory permissions without asking theoperator whether to do so in one of-ior-xmodes.

-Q file

Use the filefilein order to read tape position as stored using the dump Quick File Access mode,in one of-i,-xor-tmode.

It is recommended to set up the st driver to return logical tape positionsrather than physical before callingdump/restorewith parameter-Q.Since not all tape devices support physical tape positions those tape devicesreturn an error duringdump/restorewhen the st driver is set to the default physical setting. Please see thest(4)man page, optionMTSETDRVBUFFER, or themt(1)man page, on how to set the driver to return logical tape positions.

Before callingrestorewith parameter-Q,always make sure the st driver is set to return the same type of tape positionused during the call todump.Otherwiserestoremay 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 specifiedfilenoon a multi-file tape. File numbering starts at 1.

-T directory

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

-u

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

-v

Normallyrestoredoes its work silently. The-v(verbose) flag causes it to type the name of each file it treats preceded byits 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 filefilelistin addition to those specified on the command line. This can be used inconjunction with the-tor-xcommands. The filefilelistshould contain file names separated by newlines.filelistmay 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 notdocumented here.)

DIAGNOSTICS¶

Complains if it gets a read error. Ifyhas been specified, or the user respondsy,restorewill attempt to continue the restore.

If a backup was made using more than one tape volume,restorewill notify the user when it is time to mount the next volume. If the-xor-iflag has been specified,restorewill also ask which volume the user wishes to mount. The fastest way to extracta few files is to start with the last volume, and work towards the first volume.

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

Converting to new file system format

A dump tape created from the old file system has been loaded. It isautomatically 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 onthe tape. This is caused by tape read errors while looking for the file, andfrom 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 whenusing a dump created on an active file system.

Incremental dump too low

When doing an incremental restore, a dump that was written before the previousincremental 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 coveragewhere the previous incremental dump left off, or that has too high anincremental 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 thetape is trying to resynchronize, no extracted files have been corrupted, thoughfiles may not be found on the tape.

resync restore, skipped <num> blocks

After a dump read error,restoremay have to resynchronize itself. This message lists the number of blocks thatwere skipped over.

EXITSTATUS¶

Restoreexits with zero status on success. Tape errors are indicated with an exit codeof 1.

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

ENVIRONMENT¶

If the following environment variable exists it will be utilized byrestore:

TAPE

If no-foption was specified,restorewill use the device specified viaTAPEas the dump device.TAPEmay be of the formtapename,host:tapenameoruser@host:tapename.

TMPDIR

The directory given inTMPDIRwill be used instead of/tmpto store temporary files.

RMT

The environment variableRMTwill be used to determine the pathname of the remotermt(8)program.

RSH

Restoreuses the contents of this variable to determine the name of the remote shellcommand to use when doing a network restore (rsh, ssh etc.). If this variableis 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

SEEALSO¶

dump(8),mount(8),mke2fs(8),rmt(8)

BUGS¶

Restorecan get confused when doing incremental restores from dumps that were made onactive file systems.

A level 0 dump must be done after a full restore. Becauserestoreruns in user code, it has no control over inode allocation; thus a full dumpmust be done to get a new set of directories reflecting the new inodenumbering, 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 processID (seemktemp(3)),except when-ror-Ris used. Because-Rallows you to restart a-roperation that may have been interrupted, the temporary files should be thesame across different processes. In all other cases, the files are uniquebecause 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 runrestoreas root or use a remote shell replacement (seeRSHvariable). This is due to the previous security history ofdumpandrestore.(restoreis written to be setuid root, but we are not certain all bugs are gone from thecode - run setuid at your own risk.)

At the end of restores in-ior-xmodes (unless-ooption is in use),restorewill ask the operator whether to set the permissions on the currentdirectory. If the operator confirms this action, the permissionson the directory from whererestorewas launched will be replaced by the permissions on the dumped rootinode. Although this behaviour is not really a bug, it has proven itselfto 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 thepermissions on '/'.

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

AUTHOR¶

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

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

AVAILABILITY¶

Thedump/restorebackup suite is available from <https://dump.sourceforge.io>

HISTORY¶

Therestorecommand appeared in 4.2BSD.