| 1 | .\" Copyright (c) 1980 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement |
| 3 | .\" specifies the terms and conditions for redistribution. |
| 4 | .\" |
| 5 | .\" @(#)fsck.8 6.1 (Berkeley) %G% |
| 6 | .\" |
| 7 | .TH FSCK 8 "" |
| 8 | .UC 4 |
| 9 | .de us |
| 10 | \\$1\l'|0\(ul' |
| 11 | .. |
| 12 | .SH NAME |
| 13 | fsck \- file system consistency check and interactive repair |
| 14 | .SH SYNOPSIS |
| 15 | .B /etc/fsck |
| 16 | .B \-p |
| 17 | [ |
| 18 | filesystem ... |
| 19 | ] |
| 20 | .br |
| 21 | .B /etc/fsck |
| 22 | [ |
| 23 | .B \-b |
| 24 | block# |
| 25 | ] [ |
| 26 | .B \-y |
| 27 | ] [ |
| 28 | .B \-n |
| 29 | ] [ |
| 30 | filesystem |
| 31 | ] ... |
| 32 | .SH DESCRIPTION |
| 33 | The first form of |
| 34 | .I fsck |
| 35 | preens a standard set of filesystems or the specified file systems. |
| 36 | It is normally used in the script |
| 37 | .B /etc/rc |
| 38 | during automatic reboot. |
| 39 | In this case |
| 40 | .I fsck |
| 41 | reads the table |
| 42 | .B /etc/fstab |
| 43 | to determine which file systems to check. |
| 44 | It uses the information there to inspect groups of disks in parallel taking |
| 45 | maximum advantage of i/o overlap to check the file systems |
| 46 | as quickly as possible. |
| 47 | Normally, the root file system will be checked on pass 1, other |
| 48 | ``root'' (``a'' partition) file systems on pass 2, other |
| 49 | small file systems on separate passes (e.g. the ``d'' file systems |
| 50 | on pass 3 and the ``e'' file systems on pass 4), and finally |
| 51 | the large user file systems on the last pass, e.g. pass 5. |
| 52 | A pass number of 0 in fstab causes a disk to not be checked; similarly |
| 53 | partitions which are not shown as to be mounted ``rw'' or ``ro'' |
| 54 | are not checked. |
| 55 | .PP |
| 56 | The system takes care that only a restricted class of innocuous |
| 57 | inconsistencies can happen unless hardware or software failures intervene. |
| 58 | These are limited to the following: |
| 59 | .IP |
| 60 | Unreferenced inodes |
| 61 | .ns |
| 62 | .IP |
| 63 | Link counts in inodes too large |
| 64 | .ns |
| 65 | .IP |
| 66 | Missing blocks in the free list |
| 67 | .ns |
| 68 | .IP |
| 69 | Blocks in the free list also in files |
| 70 | .ns |
| 71 | .IP |
| 72 | Counts in the super-block wrong |
| 73 | .PP |
| 74 | These are the only inconsistencies which |
| 75 | .I fsck |
| 76 | with the |
| 77 | .B \-p |
| 78 | option will correct; if it encounters other inconsistencies, it exits |
| 79 | with an abnormal return status and an automatic reboot will then fail. |
| 80 | For each corrected inconsistency one or more lines will be printed |
| 81 | identifying the file system on which the correction will take place, |
| 82 | and the nature of the correction. After successfully correcting a file |
| 83 | system, |
| 84 | .I fsck |
| 85 | will print the number of files on that file system and the number of |
| 86 | used and free blocks. |
| 87 | .PP |
| 88 | Without the |
| 89 | .B \-p |
| 90 | option, |
| 91 | .I fsck |
| 92 | audits and interactively repairs inconsistent conditions for file systems. |
| 93 | If the file system is inconsistent the operator is prompted for concurrence |
| 94 | before each correction is attempted. |
| 95 | It should be noted that a number of the corrective actions which are not |
| 96 | fixable under the |
| 97 | .B \-p |
| 98 | option will result in some loss |
| 99 | of data. |
| 100 | The amount and severity of data lost may be determined from the diagnostic |
| 101 | output. |
| 102 | The default action for each consistency correction |
| 103 | is to wait for the operator to respond \fByes\fP or \fBno\fP. |
| 104 | If the operator does not have write permission |
| 105 | .I fsck |
| 106 | will default to a |
| 107 | .BR "\-n " action. |
| 108 | .PP |
| 109 | .I Fsck |
| 110 | has more consistency checks than |
| 111 | its predecessors |
| 112 | .IR "check, dcheck, fcheck, " "and" " icheck" |
| 113 | combined. |
| 114 | .PP |
| 115 | The following flags are interpreted by |
| 116 | .I fsck. |
| 117 | .TP 6 |
| 118 | .B \-b |
| 119 | Use the block specified immediately after the flag as |
| 120 | the super block for the file system. Block 32 is always |
| 121 | an alternate super block. |
| 122 | .TP 6 |
| 123 | .B \-y |
| 124 | Assume a yes response to all questions asked by |
| 125 | .I fsck; |
| 126 | this should be used with great caution as this is a free license |
| 127 | to continue after essentially unlimited trouble has been encountered. |
| 128 | .TP 6 |
| 129 | .B \-n |
| 130 | Assume a no response to all questions asked by |
| 131 | .I fsck; |
| 132 | do not open the file system for writing. |
| 133 | .PP |
| 134 | If no filesystems are given to |
| 135 | .I fsck |
| 136 | then a default list of file systems is read from |
| 137 | the file |
| 138 | .BR /etc/fstab . |
| 139 | .PP |
| 140 | .ne 10 |
| 141 | Inconsistencies checked are as follows: |
| 142 | .TP 6 |
| 143 | 1. |
| 144 | Blocks claimed by more than one inode or the free list. |
| 145 | .br |
| 146 | .br |
| 147 | .ns |
| 148 | .TP 6 |
| 149 | 2. |
| 150 | Blocks claimed by an inode or the free list outside the range of the file system. |
| 151 | .br |
| 152 | .br |
| 153 | .ns |
| 154 | .TP 6 |
| 155 | 3. |
| 156 | Incorrect link counts. |
| 157 | .br |
| 158 | .br |
| 159 | .ns |
| 160 | .TP 6 |
| 161 | 4. |
| 162 | Size checks: |
| 163 | .br |
| 164 | .ns |
| 165 | .IP "" 12 |
| 166 | Directory size not of proper format. |
| 167 | .br |
| 168 | .br |
| 169 | .ns |
| 170 | .TP 6 |
| 171 | 5. |
| 172 | Bad inode format. |
| 173 | .br |
| 174 | .br |
| 175 | .ns |
| 176 | .TP 6 |
| 177 | 6. |
| 178 | Blocks not accounted for anywhere. |
| 179 | .br |
| 180 | .br |
| 181 | .ns |
| 182 | .TP 6 |
| 183 | 7. |
| 184 | Directory checks: |
| 185 | .br |
| 186 | .br |
| 187 | .ns |
| 188 | .IP "" 12 |
| 189 | File pointing to unallocated inode. |
| 190 | .br |
| 191 | Inode number out of range. |
| 192 | .br |
| 193 | .br |
| 194 | .ns |
| 195 | .TP 6 |
| 196 | 8. |
| 197 | Super Block checks: |
| 198 | .br |
| 199 | .br |
| 200 | .ns |
| 201 | .IP "" 12 |
| 202 | .br |
| 203 | More blocks for inodes than there are in the file system. |
| 204 | .br |
| 205 | .br |
| 206 | .ns |
| 207 | .TP 6 |
| 208 | 9. |
| 209 | Bad free block list format. |
| 210 | .br |
| 211 | .br |
| 212 | .ns |
| 213 | .TP 6 |
| 214 | 10. |
| 215 | Total free block and/or free inode count incorrect. |
| 216 | .PP |
| 217 | Orphaned files and directories (allocated but unreferenced) are, |
| 218 | with the operator's concurrence, reconnected by |
| 219 | placing them in the |
| 220 | .B lost+found |
| 221 | directory. |
| 222 | The name assigned is the inode number. The only restriction |
| 223 | is that the directory |
| 224 | .B lost+found |
| 225 | must preexist |
| 226 | in the root of the filesystem being checked and |
| 227 | must have empty slots in which entries can be made. |
| 228 | This is accomplished by making |
| 229 | .BR lost+found , |
| 230 | copying a number of files to the directory, and then removing them |
| 231 | (before |
| 232 | .I |
| 233 | fsck |
| 234 | is executed). |
| 235 | .PP |
| 236 | Checking the raw device is almost always faster. |
| 237 | .SH FILES |
| 238 | .br |
| 239 | .ns |
| 240 | .TP 21 |
| 241 | /etc/fstab |
| 242 | contains default list of file systems to check. |
| 243 | .SH DIAGNOSTICS |
| 244 | The diagnostics produced by |
| 245 | .I fsck |
| 246 | are intended to be self-explanatory. |
| 247 | .SH "SEE ALSO" |
| 248 | fstab(5), |
| 249 | fs(5), |
| 250 | newfs(8), |
| 251 | mkfs(8), |
| 252 | crash(8V), |
| 253 | reboot(8) |
| 254 | .SH BUGS |
| 255 | Inode numbers for |
| 256 | .BR . "" |
| 257 | and |
| 258 | .BR .. "" |
| 259 | in each directory should be checked for validity. |
| 260 | .PP |
| 261 | There should be some way to start a \fBfsck \-p\fR at pass \fIn\fR. |