Checking `tar' progress
Typically, `tar' performs most operations without reporting any
information to the user except error messages. When using `tar' with
many options, particularly ones with complicated or
difficult-to-predict behavior, it is possible to make serious mistakes.
`tar' provides several options that make observing `tar' easier. These
options cause `tar' to print information as it progresses in its job,
and you might want to use them just for being more careful about what
is going on, or merely for entertaining yourself. If you have
encountered a problem when operating on an archive, however, you may
need more information than just an error message in order to solve the
problem. The following options can be helpful diagnostic tools.
Normally, the `--list' (`-t') command to list an archive prints just
the file names (one per line) and the other commands are silent. When
used with most operations, the `--verbose' (`-v') option causes `tar'
to print the name of each file or archive member as it is processed.
This and the other options which make `tar' print status information
can be useful in monitoring `tar'.
With `--create' (`-c') or `--extract' (`--get', `-x'), `--verbose'
(`-v') used once just prints the names of the files or members as they
are processed. Using it twice causes `tar' to print a longer listing
(reminiscent of `ls -l') for each member. Since `--list' (`-t')
already prints the names of the members, `--verbose' (`-v') used once
with `--list' (`-t') causes `tar' to print an `ls -l' type listing of
the files in the archive. The following examples both extract members
with long list output:
$ tar --extract --file=archive.tar --verbose --verbose
$ tar xvv archive.tar
Verbose output appears on the standard output except when an archive
is being written to the standard output, as with `tar --create --file=-
--verbose' (`tar cfv -', or even `tar cv'--if the installer let
standard output be the default archive). In that case `tar' writes
verbose output to the standard error stream.
The `--totals' option--which is only meaningful when used with
`--create' (`-c')--causes `tar' to print the total amount written to
the archive, after it has been fully created.
The `--checkpoint' option prints an occasional message as `tar'
reads or writes the archive. In fact, it print directory names while
reading the archive. It is designed for those who don't need the more
detailed (and voluminous) output of `--block-number' (`-R'), but do
want visual confirmation that `tar' is actually making forward progress.
The `--show-omitted-dirs' option, when reading an archive--with
`--list' (`-t') or `--extract' (`--get', `-x'), for example--causes a
message to be printed for each directory in the archive which is
skipped. This happens regardless of the reason for skipping: the
directory might not have been named on the command line (implicitly or
explicitly), it might be excluded by the use of the `--exclude=PATTERN'
option, or some other reason.
If `--block-number' (`-R') is used, `tar' prints, along with every
message it would normally produce, the block number within the archive
where the message was triggered. Also, supplementary messages are
triggered when reading blocks full of NULs, or when hitting end of file
on the archive. As of now, if the archive if properly terminated with
a NUL block, the reading of the file may stop before end of file is
met, so the position of end of file will not usually show when
`--block-number' (`-R') is used. Note that GNU `tar' drains the
archive before exiting when reading the archive from a pipe.
This option is especially useful when reading damaged archives, since
it helps pinpoint the damaged sections. It can also be used with
`--list' (`-t') when listing a file-system backup tape, allowing you to
choose among several backup tapes when retrieving a file later, in
favor of the tape where the file appears earliest (closest to the front
of the tape). .
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