diskdev_cmds/fsck.tproj/fsck.8

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  32 .\"     @(#)fsck.8      8.4 (Berkeley) 5/9/95
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  34 .Dd May 18, 2010
  35 .Dt FSCK 8
  36 .Os BSD 4
  37 .Sh NAME
  38 .Nm fsck
  39 .Nd filesystem consistency check and interactive repair
  40 .Sh SYNOPSIS
  41 .Nm fsck
  42 .Fl p
  43 .Op Fl f
  44 .Nm fsck
  45 .Op Fl l Ar maxparallel
  46 .Op Fl q
  47 .Op Fl y
  48 .Op Fl n
  49 .Op Fl d
  50 .Sh DESCRIPTION
  51 The first form of
  52 .Nm fsck
  53 preens a standard set of filesystems or the specified filesystems.
  54 It is normally used in the script
  55 .Pa /etc/rc
  56 during automatic reboot.
  57 Here
  58 .Nm fsck
  59 reads the filesystem descriptor table (using
  60 .Xr getfsent 3 )
  61 to determine which filesystems to check.
  62 Only partitions that have ``rw,'' ``rq'' or ``ro'' as options,
  63 and that have non-zero pass number are checked.
  64 Filesystems with pass number 1 (normally just the root filesystem)
  65 are checked one at a time.
  66 When pass 1 completes, all remaining filesystems are checked,
  67 running one process per disk drive.
  68 The disk drive containing each filesystem is inferred from the shortest prefix
  69 of the device name that ends in one or more digits; the remaining characters
  70 are assumed to be the partition designator.
  71 In preening mode,
  72 filesystems that are marked clean are skipped.
  73 Filesystems are marked clean when they are unmounted,
  74 when they have been mounted read-only, or when
  75 .Nm fsck
  76 runs on them successfully.
  77 .Pp
  78 It should be noted that
  79 .Nm fsck
  80 is now essentially a wrapper that invokes other
  81 .Pa fsck_XXX
  82 utilities as needed.  Currently,
  83 .Nm fsck
  84 can invoke
  85 .Pa fsck_hfs ,
  86 .Pa fsck_apfs ,
  87 .Pa fsck_msdos ,
  88 .Pa fsck_exfat ,
  89 and
  90 .Pa fsck_udf .
  91 If this underlying process that
  92 .Nm fsck
  93 invokes encounters serious inconsistencies or the filesystem type is not one
  94 of the above, it exits
  95 with an abnormal return status and an automatic reboot will then fail.
  96 For each corrected inconsistency one or more lines will be printed
  97 identifying the filesystem on which the correction will take place,
  98 and the nature of the correction.
  99 .Pp
 100 If sent a
 101 .Dv QUIT
 102 signal,
 103 .Nm fsck
 104 will finish the filesystem checks, then exit with an abnormal
 105 return status that causes an automatic reboot to fail.
 106 This is useful when you want to finish the filesystem checks during an
 107 automatic reboot,
 108 but do not want the machine to come up multiuser after the checks complete.
 109 .Pp
 110 Without the
 111 .Fl p
 112 option,
 113 .Nm fsck
 114 audits and interactively repairs inconsistent conditions for filesystems.
 115 It should be noted that some of the corrective actions which are not
 116 correctable under the
 117 .Fl p
 118 option will result in some loss of data.
 119 The amount and severity of data lost may be determined from the diagnostic
 120 output.
 121 If the operator does not have write permission on the filesystem
 122 .Nm fsck
 123 will default to a
 124 .Fl n
 125 action.
 126 .Pp
 127 The following flags are interpreted by
 128 .Nm fsck
 129 and passed along to the underlying tool that it spawns.
 130 .Bl -tag
 131 .It Fl f
 132 Force fsck to check `clean' filesystems when preening.
 133 .It Fl l
 134 Limit the number of parallel checks to the number specified in the following
 135 argument.
 136 By default, the limit is the number of disks, running one process per disk.
 137 If a smaller limit is given, the disks are checked round-robin, one filesystem
 138 at a time.
 139 .It Fl R
 140 Specify a particular passno number for which fsck is to check.  You may only specify 1 or 2.
 141 Only those filesystems matching that particular passno entry (if using fstab) will be checked.
 142 For more information on the passno field, see
 143 .Xr fstab 5 .
 144 .It Fl p
 145 "Preen" mode, described above.
 146 .It Fl q
 147 Do a quick check to determine if the filesystem was unmounted cleanly.
 148 .It Fl y
 149 Assume a yes response to all questions asked by
 150 .Nm fsck ;
 151 this should be used with great caution as this is a free license
 152 to continue after essentially unlimited trouble has been encountered.
 153 .It Fl n
 154 Assume a no response to all questions asked by
 155 .Nm fsck
 156 except for
 157 .Ql CONTINUE? ,
 158 which is assumed to be affirmative;
 159 do not open the filesystem for writing.
 160 .El
 161 .Pp
 162 If no filesystems are given to
 163 .Nm fsck
 164 then a default list of filesystems is read using
 165 .Xr getfsent 3 .
 166 .Pp
 167 Because of inconsistencies between the block device and the buffer cache,
 168 the raw device should always be used.
 169 .Sh SEE ALSO
 170 .Xr fs 5 ,
 171 .Xr fsck_hfs 8 ,
 172 .Xr fsck_apfs 8 ,
 173 .Xr fsck_msdos 8 ,
 174 .Xr getfsent 3 ,
 175 .Xr fstab 5,
 176 .Xr reboot 8