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235 lines
6.5 KiB
Groff
235 lines
6.5 KiB
Groff
.\" -*- nroff -*-
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.TH BADBLOCKS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
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.SH NAME
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badblocks \- search a device for bad blocks
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.SH SYNOPSIS
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.B badblocks
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[
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.B \-svwnfBX
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]
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[
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.B \-b
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.I block-size
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]
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[
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.B \-c
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.I blocks_at_once
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]
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[
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.B \-e
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.I max_bad_blocks
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]
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[
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.B \-d
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.I read_delay_factor
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]
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[
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.B \-i
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.I input_file
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]
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[
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.B \-o
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.I output_file
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]
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[
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.B \-p
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.I num_passes
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]
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[
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.B \-t
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.I test_pattern
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]
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.I device
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[
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.I last-block
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] [
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.I first-block
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]
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.SH DESCRIPTION
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.B badblocks
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is used to search for bad blocks on a device (usually a disk partition).
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.I device
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is the special file corresponding to the device (e.g
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.IR /dev/hdc1 ).
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.I last-block
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is the last block to be checked; if it is not specified, the last block
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on the device is used as a default.
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.I first-block
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is an optional parameter specifying the starting block number
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for the test, which allows the testing to start in the middle of the
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disk. If it is not specified the first block on the disk is used as a default.
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.PP
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.B Important note:
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If the output of
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.B badblocks
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is going to be fed to the
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.B e2fsck
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or
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.B mke2fs
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programs, it is important that the block size is properly specified,
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since the block numbers which are generated are very dependent on the
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block size in use by the filesystem.
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For this reason, it is strongly recommended that
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users
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.B not
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run
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.B badblocks
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directly, but rather use the
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.B \-c
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option of the
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.B e2fsck
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and
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.B mke2fs
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programs.
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.SH OPTIONS
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.TP
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.BI \-b " block-size"
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Specify the size of blocks in bytes. The default is 1024.
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.TP
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.BI \-c " number of blocks"
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is the number of blocks which are tested at a time. The default is 64.
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.TP
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.BI \-e " max bad block count"
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Specify a maximum number of bad blocks before aborting the test. The
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default is 0, meaning the test will continue until the end of the test
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range is reached.
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.TP
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.BI \-d " read delay factor"
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This parameter, if passed and non-zero, will cause bad blocks to sleep
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between reads if there were no errors encountered in the read
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operation; the delay will be calculated as a percentage of the time it
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took for the read operation to be performed. In other words, a value of
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100 will cause each read to be delayed by the amount the previous read
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took, and a value of 200 by twice the amount.
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.TP
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.B \-f
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Normally, badblocks will refuse to do a read/write or a non-destructive
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test on a device which is mounted, since either can cause the system to
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potentially crash and/or damage the filesystem even if it is mounted
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read-only. This can be overridden using the
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.B \-f
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flag, but should almost never be used --- if you think you're smarter
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than the
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.B badblocks
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program, you almost certainly aren't. The only time when this option
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might be safe to use is if the /etc/mtab file is incorrect, and the device
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really isn't mounted.
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.TP
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.BI \-i " input_file"
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Read a list of already existing known bad blocks.
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.B Badblocks
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will skip testing these blocks since they are known to be bad. If
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.I input_file
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is specified as "-", the list will be read from the standard input.
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Blocks listed in this list will be omitted from the list of
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.I new
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bad blocks produced on the standard output or in the output file.
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The
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.B \-b
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option of
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.BR dumpe2fs (8)
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can be used to retrieve the list of blocks currently marked bad on
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an existing filesystem, in a format suitable for use with this option.
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.TP
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.B \-n
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Use non-destructive read-write mode. By default only a non-destructive
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read-only test is done. This option must not be combined with the
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.B \-w
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option, as they are mutually exclusive.
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.TP
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.BI \-o " output_file"
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Write the list of bad blocks to the specified file. Without this option,
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.B badblocks
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displays the list on its standard output. The format of this file is suitable
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for use by the
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.
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.B \-l
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option in
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.BR e2fsck (8)
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or
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.BR mke2fs (8).
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.TP
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.BI \-p " num_passes"
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Repeat scanning the disk until there are no new blocks discovered in
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num_passes consecutive scans of the disk.
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Default is 0, meaning
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.B badblocks
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will exit after the first pass.
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.TP
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.B \-s
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Show the progress of the scan by writing out rough percentage completion
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of the current badblocks pass over the disk. Note that badblocks may do
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multiple test passes over the disk, in particular if the
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.B \-p
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or
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.B \-w
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option is requested by the user.
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.TP
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.BI \-t " test_pattern"
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Specify a test pattern to be read (and written) to disk blocks. The
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.I test_pattern
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may either be a numeric value between 0 and ULONG_MAX-1 inclusive, or the word
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"random", which specifies that the block should be filled with a random
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bit pattern.
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For read/write (\fB-w\fR) and non-destructive (\fB-n\fR) modes,
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one or more test patterns may be specified by specifying the
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.B -t
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option for each test pattern desired. For
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read-only mode only a single pattern may be specified and it may not be
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"random". Read-only testing with a pattern assumes that the
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specified pattern has previously been written to the disk - if not, large
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numbers of blocks will fail verification.
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If multiple patterns
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are specified then all blocks will be tested with one pattern
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before proceeding to the next pattern.
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.TP
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.B \-v
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Verbose mode. Will write the number of read errors, write errors and data-
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corruptions to stderr.
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.TP
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.B \-w
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Use write-mode test. With this option,
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.B badblocks
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scans for bad blocks by writing some patterns (0xaa, 0x55, 0xff, 0x00) on
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every block of the device, reading every block and comparing the contents.
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This option may not be combined with the
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.B \-n
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option, as they are mutually exclusive.
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.TP
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.B \-B
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Use buffered I/O and do not use Direct I/O, even if it is available.
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.TP
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.B \-X
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Internal flag only to be used by
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.BR e2fsck (8)
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and
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.BR mke2fs (8).
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It bypasses the exclusive mode in-use device safety check.
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.SH WARNING
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Never use the
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.B \-w
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option on a device containing an existing file system.
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This option erases data! If you want to do write-mode testing on
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an existing file system, use the
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.B \-n
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option instead. It is slower, but it will preserve your data.
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.PP
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The
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.B \-e
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option will cause badblocks to output a possibly incomplete list of
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bad blocks. Therefore it is recommended to use it only when one wants
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to know if there are any bad blocks at all on the device, and not when
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the list of bad blocks is wanted.
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.SH AUTHOR
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.B badblocks
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was written by Remy Card <Remy.Card@linux.org>. Current maintainer is
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Theodore Ts'o <tytso@alum.mit.edu>. Non-destructive read/write test
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implemented by David Beattie <dbeattie@softhome.net>.
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.SH AVAILABILITY
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.B badblocks
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is part of the e2fsprogs package and is available from
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http://e2fsprogs.sourceforge.net.
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.SH SEE ALSO
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.BR e2fsck (8),
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.BR mke2fs (8)
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