-A archive file implementation

[dump.git] / restore / restore.8.in

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.\"	$Id: restore.8.in,v 1.24 2002/01/25 14:59:53 stelian Exp $
.\"
.Dd __DATE__
.Dt RESTORE 8
.Os "restore __VERSION__"
.Sh NAME
.Nm restore
.Nd "restore files or file systems from backups made with dump"
.Sh SYNOPSIS
.Nm restore
.Fl C
.Op Fl cklMvVy
.Op Fl b Ar blocksize
.Op Fl D Ar filesystem
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl L Ar limit
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Nm restore
.Fl i
.Op Fl achklmMNuvVy
.Op Fl A Ar file
.Op Fl b Ar blocksize
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl Q Ar file
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Nm restore
.Fl R
.Op Fl cklMNuvVy
.Op Fl b Ar blocksize
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Nm restore
.Fl r
.Op Fl cklMNuvVy
.Op Fl b Ar blocksize
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Nm restore
.Fl t
.Op Fl chklMNuvVy
.Op Fl A Ar file
.Op Fl b Ar blocksize
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl Q Ar file
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Op Fl X Ar filelist
.Op file ...
.Nm restore
.Fl x
.Op Fl achklmMNuvVy
.Op Fl A Ar file
.Op Fl b Ar blocksize
.Op Fl f Ar file
.Op Fl F Ar script
.Op Fl Q Ar file
.Op Fl s Ar fileno
.Op Fl T Ar directory
.Op Fl X Ar filelist
.Op file ...
.Pp
.in
(The
.Bx 4.3
option syntax is implemented for backward compatibility but
is not documented here.)
.Sh DESCRIPTION
The
.Nm restore
command performs the inverse function of
.Xr 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.
.Nm Restore
works across a network;
to do this see the
.Fl f
flag described below.
Other arguments to the command are file or directory
names specifying the files that are to be restored.
Unless the
.Fl h
flag is specified (see below),
the appearance of a directory name refers to
the files and (recursively) subdirectories of that directory.
.Pp
Exactly one of the following flags is required:
.Bl -tag -width Ds
.It Fl C
This mode allows comparison of files from a dump.
.Nm 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
.Fl L
flag described below.
.It Fl i
This mode allows interactive restoration of files from a dump.
After reading in the directory information from the dump,
.Nm 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.
.Bl -tag -width Fl
.It Ic add Op Ar 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 descendents are
added to the extraction list
(unless the
.Fl h
flag is specified on the command line).
Files that are on the extraction list are prepended with a
.Dq \&*
when they are listed by 
.Ic ls .
.It Ic \&cd Ar arg
Change the current working directory to the specified argument.
.It Ic delete Op Ar 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 descendents are
deleted from the extraction list
(unless the
.Fl 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.
.It Ic extract
All files on the extraction list are extracted
from the dump.
.Nm 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.
.It Ic help
List a summary of the available commands.
.It Ic \&ls Op Ar arg
List the current or specified directory.
Entries that are directories are appended with a
.Dq \&* .
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.
.It Ic pwd
Print the full pathname of the current working directory.
.It Ic quit
Restore immediately exits,
even if the extraction list is not empty.
.It Ic 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.
.It Ic verbose
The sense of the 
.Fl v
flag is toggled.
When set, the verbose flag causes the 
.Ic ls
command to list the inode numbers of all entries.
It also causes
.Nm restore
to print out information about each file as it is extracted.
.El
.It Fl R
.Nm Restore
requests a particular tape of a multi-volume set on which to restart
a full restore
(see the
.Fl r
flag below).
This is useful if the restore has been interrupted.
.It Fl r
Restore (rebuild) a file system.
The target file system should be made pristine with
.Xr mke2fs 8 ,
mounted, and the user
.Xr cd Ns 'd
into the pristine file system
before starting the restoration of the initial level 0 backup. If the
level 0 restores successfully, the
.Fl r
flag may be used to restore
any necessary incremental backups on top of the level 0.
The
.Fl 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:
.Bd -literal -offset indent
mke2fs /dev/sda1
mount /dev/sda1 /mnt
cd /mnt

restore rf /dev/st0
.Ed
.Pp
Note that 
.Nm restore
leaves a file 
.Pa restoresymtable
in the root directory to pass information between incremental
restore passes.
This file should be removed when the last incremental has been
restored.
.Pp
.Nm Restore ,
in conjunction with
.Xr mke2fs 8
and
.Xr dump 8 ,
may be used to modify file system parameters
such as size or block size.
.It Fl 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
.Fl h
flag has been specified.
Note that the
.Fl t
flag replaces the function of the old
.Xr dumpdir 8
program.
See also the
.Fl X
option below.
.ne 1i
.It Fl 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
.Fl 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
.Fl h
flag has been specified.
See also the
.Fl X
option below.
.El
.Pp
The following additional options may be specified:
.Bl -tag -width Ds
.It Fl a
In 
.Fl i
or
.Fl x
mode, 
.Nm 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
be reading only the interesting volumes). The 
.Fl 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.
.It Fl A Ar archive_file
Read the table of contents from
.Ar archive_file
instead of the media. This option can be used in combination with the 
.Fl t, 
.Fl i, 
or 
.Fl x 
options, making it possible to check whether files are on the media 
without having to mount the media. 
.It Fl b Ar blocksize
The number of kilobytes per dump record.
If the
.Fl b
option is not specified,
.Nm restore
tries to determine the media block size dynamically.
.It Fl c
Normally,
.Nm restore
will try to determine dynamically whether the dump was made from an
old (pre-4.4) or new format file system.  The
.Fl c
flag disables this check, and only allows reading a dump in the old
format.
.It Fl D Ar filesystem
The
.Fl D
flag allows the user to specify the filesystem name when using
.Nm restore
with the
.Fl C
option to check the backup.
.It Fl f Ar file
Read the backup from
.Ar file ;
.Ar file
may be a special device file
like
.Pa /dev/st0
(a tape drive),
.Pa /dev/sda1
(a disk drive),
an ordinary file,
or
.Ql Fl
(the standard input).
If the name of the file is of the form
.Dq host:file 
or
.Dq user@host:file ,
.Nm restore
reads from the named file on the remote host using
.Xr rmt 8 .
.Pp
.It Fl F Ar 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 
.Nm
should continue without asking the user to change the tape, 1 if 
.Nm
should continue but ask the user to change the tape. 
Any other exit code will cause
.Nm
to abort.
For security reasons,
.Nm
reverts back to the real user ID and the real group ID before 
running the script.
.It Fl h
Extract the actual directory, 
rather than the files that it references.
This prevents hierarchical restoration of complete subtrees
from the dump.
.It Fl k
Use Kerberos authentication when contacting the remote tape server.
(Only available if this options was enabled when
.Nm restore
was compiled.)
.It Fl 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 
.Nm restore
will fail to access it correctly.
.It Fl L Ar limit
The
.Fl L
flag allows the user to specify a maximal number of miscompares
when using
.Nm restore
with the
.Fl C
option to check the backup. If this limit is reached, 
.Nm restore
will abort with an error message. A value of 0 (the default value) 
disables the check.
.It Fl 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.
.It Fl M
Enables the multi-volume feature (for reading dumps made using
the 
.Fl M
option of dump). The name specified with
.Fl f
is treated as a prefix and
.Nm
tries to read in sequence from <prefix>001, <prefix>002 etc. 
.It Fl N
The
.Fl N
flag causes
.Nm
to perform a full execution as requested by one of
.Fl i,
.Fl R,
.Fl r,
.Fl t
or
.Fl x
command without actually writing any file on disk.
.It Fl Q Ar file
Use the file
.Ar file
in order to read tape position as stored using the dump Quick File
Access mode, in one of 
.Fl i,
.Fl x
or
.Fl t
mode.
.Pp
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 man page, option MTSETDRVBUFFER, or the mt man
page, on how to set the driver to return logical tape positions.
.Pp
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.
.Pp
This option can be used when restoring from local or remote tapes 
(see above) or from local or remote files.
.It Fl s Ar fileno
Read from the specified
.Ar fileno
on a multi-file tape.
File numbering starts at 1.
.It Fl T Ar directory
The
.Fl 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.
.It Fl 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
.Fl u
(unlink) flag causes restore to remove old entries before attempting
to create new ones.
.It Fl v
Normally
.Nm restore
does its work silently.
The
.Fl v
(verbose)
flag causes it to type the name of each file it treats
preceded by its file type.
.It Fl V
Enables reading multi-volume non-tape mediums like CDROMs.
.It Fl X Ar filelist
Read list of files to be listed or extracted from the text file
.Ar filelist
in addition to those specified on the command line. This can be used in 
conjunction with the
.Fl t
or
.Fl x
commands. The file
.Ar filelist
should contain file names separated by newlines.
.Ar filelist
may be an ordinary file or
.Ql Fl
(the standard input).
.It Fl 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.
.El
.Sh DIAGNOSTICS
Complains if it gets a read error.
If 
.Fl y
has been specified, or the user responds
.Ql y ,
.Nm restore
will attempt to continue the restore.
.Pp
If a backup was made using more than one tape volume,
.Nm restore
will notify the user when it is time to mount the next volume.
If the
.Fl x
or
.Fl i
flag has been specified,
.Nm 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.
.Pp
There are numerous consistency checks that can be listed by
.Nm restore .
Most checks are self-explanatory or can
.Dq never happen .
Common errors are given below.
.Pp
.Bl -tag -width Ds -compact
.It 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.
.Pp
.It <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.
.Pp
.It 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.
.Pp
.It 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.
.Pp
.It 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.
.Pp
.It Tape read error while restoring <filename>
.It Tape read error while skipping over inode <inumber>
.It 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.
.Pp
.It resync restore, skipped <num> blocks
After a dump read error, 
.Nm restore
may have to resynchronize itself.
This message lists the number of blocks that were skipped over.
.El
.Pp
.Nm Restore
exits with zero status on success.
Tape errors are indicated with an exit code of 1.
.Pp
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.
.Sh ENVIRONMENT
If the following environment variable exists it will be utilized by
.Nm restore :
.Pp
.Bl -tag -width "TMPDIR" -compact
.It Ev TAPE
If no -f option was specified,
.Nm
will use the device specified via
.Ev TAPE
as the dump device.
.Ev TAPE
may be of the form
.Qq tapename ,
.Qq host:tapename
or
.Qq user@host:tapename .
.It Ev TMPDIR
The directory given in
.Ev TMPDIR
will be used
instead of
.Pa /tmp
to store temporary files.
.It Ev RMT
The environment variable
.Ev RMT
will be used to determine the pathname of the remote
.Xr rmt 8
program.
.It Ev RSH
.Nm 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,
.Xr rcmd 3
will be used, but only root will be able to do a network restore.
.El
.Sh FILES
.Bl -tag -width "./restoresymtable" -compact
.It Pa /dev/st0
the default tape drive
.It Pa /tmp/rstdir*
file containing directories on the tape
.It Pa /tmp/rstmode*
owner, mode, and time stamps for directories
.It Pa \&./restoresymtable
information passed between incremental restores
.El
.Sh SEE ALSO
.Xr dump 8 ,
.Xr mount 8 ,
.Xr mke2fs 8 ,
.Xr rmt 8
.Sh BUGS
.Nm Restore
can get confused when doing incremental restores from
dumps that were made on active file systems.
.Pp
A level 0 dump must be done after a full restore.
Because 
.Nm 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.
.Pp
The temporary files
.Pa /tmp/rstdir*
and
.Pa /tmp/rstmode*
are generated with a unique name based on the date of the dump
and the process ID (see
.Xr mktemp 3 ),
except when
.Fl r
or
.Fl R
is used.
Because
.Fl R
allows you to restart a
.Fl 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.
.Pp
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 restore code - run setuid at your own risk.)
.Sh AUTHOR
The
.Nm 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).
.Pp
Starting with 0.4b5, the new maintainer is Stelian Pop
.br
<stelian@popies.net>.
.Sh AVAILABILITY
The
.Nm dump/restore
backup suite is available from 
.br
http://dump.sourceforge.net
.Sh HISTORY
The
.Nm restore
command appeared in
.Bx 4.2 .