1BLOCKDEV(8) System Administration BLOCKDEV(8)
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6 blockdev - call block device ioctls from the command line
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9 blockdev [-q] [-v] command [command...] device [device...]
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11 blockdev --report [device...]
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13 blockdev -h|-V
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16 The utility blockdev allows one to call block device ioctls from the
17 command line.
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20 -q
21 Be quiet.
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23 -v
24 Be verbose.
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26 --report
27 Print a report for the specified device. It is possible to give
28 multiple devices. If none is given, all devices which appear in
29 /proc/partitions are shown. Note that the partition StartSec is in
30 512-byte sectors.
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32 -h, --help
33 Display help text and exit.
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35 -V, --version
36 Print version and exit.
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39 It is possible to give multiple devices and multiple commands.
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41 --flushbufs
42 Flush buffers.
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44 --getalignoff
45 Get alignment offset.
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47 --getbsz
48 Print the blocksize in bytes. This size does not describe device
49 topology. It’s the size used internally by the kernel and it may be
50 modified (for example) by filesystem driver on mount.
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52 --getdiscardzeroes
53 Get discard zeroes support status.
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55 --getdiskseq
56 Get disk sequence number.
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58 --getfra
59 Get filesystem readahead in 512-byte sectors.
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61 --getiomin
62 Get minimum I/O size.
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64 --getioopt
65 Get optimal I/O size.
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67 --getmaxsect
68 Get max sectors per request.
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70 --getpbsz
71 Get physical block (sector) size.
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73 --getra
74 Print readahead (in 512-byte sectors).
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76 --getro
77 Get read-only. Print 1 if the device is read-only, 0 otherwise.
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79 --getsize64
80 Print device size in bytes.
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82 --getsize
83 Print device size (32-bit!) in sectors. Deprecated in favor of the
84 --getsz option.
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86 --getss
87 Print logical sector size in bytes - usually 512.
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89 --getsz
90 Get size in 512-byte sectors.
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92 --rereadpt
93 Reread partition table
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95 --setbsz bytes
96 Set blocksize. Note that the block size is specific to the current
97 file descriptor opening the block device, so the change of block
98 size only persists for as long as blockdev has the device open, and
99 is lost once blockdev exits.
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101 --setfra sectors
102 Set filesystem readahead (same as --setra on 2.6 kernels).
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104 --setra sectors
105 Set readahead (in 512-byte sectors).
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107 --setro
108 Set read-only. The currently active access to the device may not be
109 affected by the change. For example, a filesystem already mounted
110 in read-write mode will not be affected. The change applies after
111 remount.
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113 --setrw
114 Set read-write.
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117 blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.
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120 For bug reports, use the issue tracker at
121 https://github.com/util-linux/util-linux/issues.
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124 The blockdev command is part of the util-linux package which can be
125 downloaded from Linux Kernel Archive
126 <https://www.kernel.org/pub/linux/utils/util-linux/>.
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130util-linux 2.39.2 2023-08-17 BLOCKDEV(8)