restore.8

早期freebsd实现

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.\"     @(#)restore.8	8.2 (Berkeley) 12/11/93
.\"
.Dd December 11, 1993
.Dt RESTORE 8
.Os BSD 4
.Sh NAME
.Nm restore
.Nd "restore files or file systems from backups made with dump"
.Sh SYNOPSIS
.Nm restore
.Ar key
.Op Ar name Ar ...
.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.
The actions
of
.Nm restore
are controlled by the given
.Cm key ,
which
is a string of characters containing
at most one function letter and possibly
one or more function modifiers.
Other arguments to the command are file or directory
names specifying the files that are to be restored.
Unless the
.Cm h
key is specified (see below),
the appearance of a directory name refers to
the files and (recursively) subdirectories of that directory.
.Pp
The function portion of
the key is specified by one of the following letters:
.Bl -tag -width Ds
.It Cm r
Restore (rebuild a file system).
The target file system should be made pristine with
.Xr newfs 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
.Cm r
key may be used to restore
any necessary incremental backups on top of the level 0.
The
.Cm r
key precludes an interactive file extraction and can be
detrimental to one's health if not used carefully (not to mention
the disk). An example:
.Bd -literal -offset indent
newfs /dev/rrp0g eagle
mount /dev/rp0g /mnt
cd /mnt

restore rf /dev/rst8
.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 newfs 8
and
.Xr dump 8 ,
may be used to modify file system parameters
such as size or block size.
.It Cm R
.Nm Restore
requests a particular tape of a multi volume set on which to restart
a full restore
(see the
.Cm r
key above).
This is useful if the restore has been interrupted.
.It Cm 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
.Cm h
key is not specified,
the directory is recursively extracted.
The owner, modification time,
and mode are restored (if possible).
If no file argument is given,
then the root directory is extracted,
which results in the entire content of the
backup being extracted,
unless the
.Cm h
key has been specified.
.It Cm t
The names of the specified files are listed if they occur
on the backup.
If no file argument is given,
then the root directory is listed,
which results in the entire content of the
backup being listed,
unless the
.Cm h
key has been specified.
Note that the
.Cm t
key replaces the function of the old
.Xr dumpdir 8
program.
.It Cm 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
.Cm h
key is specified on the command line).
Files that are on the extraction list are prepended with a ``*''
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
.Cm h
key 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 the files that are 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 ``/''.
Entries that have been marked for extraction are prepended with a ``*''.
If the verbose key 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 the 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 
.Cm v
key is toggled.
When set, the verbose key 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
.El
.Pp
The following characters may be used in addition to the letter
that selects the function desired.
.Bl -tag -width Ds
.It Cm b
The next argument to 
.Nm restore
is used as the block size of the media (in kilobytes).
If the
.Fl b
option is not specified,
.Nm restore
tries to determine the media block size dynamically.
.It Cm f
The next argument to 
.Nm restore
is used as the name of the archive instead
of
.Pa /dev/rmt? . 
If the name of the file is of the form
.Dq host:file ,
.Nm restore
reads from the named file on the remote host using
.Xr rmt 8 .
If the name of the file is
.Ql Fl ,
.Nm restore
reads from standard input.
Thus,
.Xr dump 8
and
.Nm restore
can be used in a pipeline to dump and restore a file system
with the command
.Bd -literal -offset indent
dump 0f - /usr | (cd /mnt; restore xf -)
.Ed
.Pp
.It Cm h
.Nm Restore
extracts the actual directory, 
rather than the files that it references.
This prevents hierarchical restoration of complete subtrees
from the dump.
.It Cm m
.Nm Restore
will 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 Cm s
The next argument to
.Nm restore
is a number which
selects the file on a multi-file dump tape.  File numbering
starts at 1.
.It Cm v
Normally
.Nm restore
does its work silently.
The
.Cm v
(verbose)
key causes it to type the name of each file it treats
preceded by its file type.
.It Cm y
.Nm Restore
will not ask whether it should abort the restore if it gets an error.
It will always try to skip over the bad block(s) and continue as
best it can.
.El
.Sh DIAGNOSTICS
Complaints about bad key characters.
.Pp
Complaints if it gets a read error.
If 
.Cm 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
.Cm x
or
.Cm i
key 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 ``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 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 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,
then its contents are probably partially wrong.
If an inode is being skipped or the tape is trying to resynchronize,
then 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
.Sh FILES
.Bl -tag -width "./restoresymtable" -compact
.It Pa /dev/rmt?
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 newfs 8 ,
.Xr mount 8 ,
.Xr mkfs 8 ,
.Xr rmt 8
.Sh BUGS
.Nm Restore
can get confused when doing incremental restores from
dump that were made on active file systems.
.Pp
A level zero dump must be done after a full restore.
Because restore runs in user code,
it has no control over inode allocation;
thus a full restore must be done to get a new set of directories
reflecting the new inode numbering,
even though the contents of the files is unchanged.
.Sh HISTORY
The
.Nm restore
command appeared in
.Bx 4.2 .