btar(1) CLIX btar(1)
NAME
btar - Archives tape files
SYNOPSIS
btar [key] [name]
FLAGS
r Writes the named files on the end of the tape. This function is
referred to as the replace function. The c function implies this
function.
x Extracts the named files from the tape. If a named file matches a
directory whose contents have been written onto the tape, this
directory is (recursively) extracted. The owner, modification time,
and mode are restored (if possible). If no files argument is given,
the entire content of the tape is extracted. Note that if several
files with the same name are on the tape, the last one overwrites all
earlier ones.
t Lists the names and other information for the specified files each
time that they occur on the tape. When used with the -v flag, the
listing is similar to the format produced by the ls -l command. If no
files argument is given, all the names on the tape are listed.
u Adds the named files to the tape if they are not already there or if
they have been modified since put on the tape.
c Creates a new tape; writing begins at the beginning of the tape,
instead of after the last file. This function implies the r function.
The following characters may be used in addition to the letter that
selects the desired function.
p Restores files to their original modes, ignoring the present
umask. Setuid and sticky bit information will also be
restored to the superuser.
h Follows symbolic links as if they were normal files or
directories. Normally, btar does not follow symbolic links.
B Forces input and output blocking to 20 blocks per record.
This flag allows btar to work across a communications channel
where the blocking may not be maintained.
C Allows multiple directories not related by a close common
parent to be archived using short relative pathnames. The
btar command will change directories (see chdir) to any
directory preceded by -C. For example, to archive files from
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btar(1) CLIX btar(1)
/usr/include and from /etc, enter the following:
btar c -C/usr/include -C/etc
0, ... ,9 Selects an alternate drive on which the tape is mounted. The
default device is drive 0 at 1600 bpi, which is normally
/dev/rmt8.
v Displays the name of each file btar treats, preceded by the
function letter. The btar command normally does its work
silently. When used with the t function, v gives more
information about the tape entries than just the name.
w Displays the action to be taken, followed by the name of the
file, and then wait for the user's confirmation. If a word
beginning with y is given, the action is performed. Any other
input cancels the action. This modifier is not valid with the
t function.
f special Uses special as the name of the archive instead of /dev/rmt?.
If the name of the file is -, btar writes to the stdout or
reads from the stdin, whichever is appropriate. Thus, btar
can be used as the head or tail of a pipeline. The btar
command can also be used to move hierarchies with the command:
cd fromdir; btar cf - . | (cd todir; btar xf -)
b blocks Uses blocks as the blocking factor for tape records. The
maximum value of 20 is the default. This flag should only be
used with raw magnetic tape archives (see the f flag). The
block size is determined automatically when reading tapes (key
functions t and x).
l Displays messages if btar cannot resolve all of the links to
the files being dumped. If l is not specified, no error
messages are displayed.
m Forces btar not to restore the modification times. The
modification time of the file will be the time of extraction.
o Suppresses directory information. On output, btar normally
places information specifying owner and modes of directories
in the archive. Former versions, when encountering this
information, will display an error message of the form:
name: cannot create.
DESCRIPTION
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btar(1) CLIX btar(1)
The btar command saves to and restores from multiple files on a special
file (usually magnetic tape). Its actions are controlled by the key
argument. The key is a string of characters containing one function
letter (c, r, t, u, or x) and possibly followed by one or more modifiers
(v, w, f, o, 0, ... ,9, b, p, l, m, h, B, and C). Other arguments to btar
are file or directory names specifying which files to dump or restore. A
directory name refers to the files and (recursively) subdirectories of
that directory.
EXAMPLES
1. The following command will create a btar archive of the current
directory on SCSI device 5:
btar -cvf /dev/rmt/mt5 .
This command will use the verbose flag, and will include hidden files.
2. The following command will extract all of a btar archive from SCSI
device 6, using the verbose flag:
btar xvf /dev/rmt/mt6
FILES
/dev/rmt? Tape device file.
/tmp/tar* Temporary file used by btar.
NOTES
There is no way to ask for the n-th occurrence of a file.
Tape errors are handled ungracefully.
The r and u flags will not work with cartridge tape drives.
The u flag can be slow.
The b flag should not be used with archives that are going to be updated.
The current magnetic tape driver cannot backspace raw magnetic tape. If
the archive is on a disk file, the b flag should not be used at all,
because updating an archive stored on disk can destroy it.
The current limit on filename length is 100 characters.
The btar command doesn't copy empty directories or special files.
When specifying keys, the hyphen (-) symbol is optional.
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btar(1) CLIX btar(1)
DIAGNOSTICS
The btar command reports messages in the following cases:
⊕ Bad key characters and tape read/write errors.
⊕ Sufficient memory is not available to hold the link tables.
EXIT VALUES
Exit values are not valid.
RELATED INFORMATION
Commands: tar(1), umask(1), ls(1)
Functions: chdir(2)
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