1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)fsck.8 8.3 (Berkeley) 11/29/94 7.\" 8.Dd 9.Dt FSCK 8 10.Os BSD 4 11.Sh NAME 12.Nm fsck 13.Nd filesystem consistency check and interactive repair 14.Sh SYNOPSIS 15.Nm fsck 16.Fl p 17.Op Fl m Ar mode 18.Nm fsck 19.Op Fl b Ar block# 20.Op Fl c Ar level 21.Op Fl l Ar maxparallel 22.Op Fl y 23.Op Fl n 24.Op Fl m Ar mode 25.Op Ar filesystem 26.Ar ... 27.Sh DESCRIPTION 28The first form of 29.Nm fsck 30preens a standard set of filesystems or the specified filesystems. 31It is normally used in the script 32.Pa /etc/rc 33during automatic reboot. 34Here 35.Nm fsck 36reads the table 37.Pa /etc/fstab 38to determine which filesystems to check. 39Only partitions in fstab that are mounted ``rw,'' ``rq'' or ``ro'' 40and that have non-zero pass number are checked. 41Filesystems with pass number 1 (normally just the root filesystem) 42are checked one at a time. 43When pass 1 completes, all remaining filesystems are checked, 44running one process per disk drive. 45The disk drive containing each filesystem is inferred from the longest prefix 46of the device name that ends in a digit; the remaining characters are assumed 47to be the partition designator. 48.Pp 49The kernel takes care that only a restricted class of innocuous filesystem 50inconsistencies can happen unless hardware or software failures intervene. 51These are limited to the following: 52.Bl -item -compact 53.It 54Unreferenced inodes 55.It 56Link counts in inodes too large 57.It 58Missing blocks in the free map 59.It 60Blocks in the free map also in files 61.It 62Counts in the super-block wrong 63.El 64.Pp 65These are the only inconsistencies that 66.Nm fsck 67with the 68.Fl p 69option will correct; if it encounters other inconsistencies, it exits 70with an abnormal return status and an automatic reboot will then fail. 71For each corrected inconsistency one or more lines will be printed 72identifying the filesystem on which the correction will take place, 73and the nature of the correction. After successfully correcting a filesystem, 74.Nm fsck 75will print the number of files on that filesystem, 76the number of used and free blocks, 77and the percentage of fragmentation. 78.Pp 79If sent a 80.Dv QUIT 81signal, 82.Nm fsck 83will finish the filesystem checks, then exit with an abnormal 84return status that causes an automatic reboot to fail. 85This is useful when you want to finish the filesystem checks during an 86automatic reboot, 87but do not want the machine to come up multiuser after the checks complete. 88.Pp 89Without the 90.Fl p 91option, 92.Nm fsck 93audits and interactively repairs inconsistent conditions for filesystems. 94If the filesystem is inconsistent the operator is prompted for concurrence 95before each correction is attempted. 96It should be noted that some of the corrective actions which are not 97correctable under the 98.Fl p 99option will result in some loss of data. 100The amount and severity of data lost may be determined from the diagnostic 101output. 102The default action for each consistency correction 103is to wait for the operator to respond 104.Li yes 105or 106.Li no . 107If the operator does not have write permission on the filesystem 108.Nm fsck 109will default to a 110.Fl n 111action. 112.Pp 113.Nm Fsck 114has more consistency checks than 115its predecessors 116.Em check , dcheck , fcheck , 117and 118.Em icheck 119combined. 120.Pp 121The following flags are interpreted by 122.Nm fsck . 123.Bl -tag -width indent 124.It Fl b 125Use the block specified immediately after the flag as 126the super block for the filesystem. Block 32 is usually 127an alternate super block. 128.It Fl l 129Limit the number of parallel checks to the number specified in the following 130argument. 131By default, the limit is the number of disks, running one process per disk. 132If a smaller limit is given, the disks are checked round-robin, one filesystem 133at a time. 134.It Fl m 135Use the mode specified in octal immediately after the flag as the 136permission bits to use when creating the 137.Pa lost+found 138directory rather than the default 1777. 139In particular, systems that do not wish to have lost files accessible 140by all users on the system should use a more restrictive 141set of permissions such as 700. 142.It Fl y 143Assume a yes response to all questions asked by 144.Nm fsck ; 145this should be used with great caution as this is a free license 146to continue after essentially unlimited trouble has been encountered. 147.It Fl n 148Assume a no response to all questions asked by 149.Nm fsck 150except for 151.Ql CONTINUE? , 152which is assumed to be affirmative; 153do not open the filesystem for writing. 154.It Fl c 155Convert the filesystem to the specified level. 156Note that the level of a filesystem can only be raised. 157.Bl -tag -width indent 158There are currently four levels defined: 159.It 0 160The filesystem is in the old (static table) format. 161.It 1 162The filesystem is in the new (dynamic table) format. 163.It 2 164The filesystem supports 32-bit uid's and gid's, 165short symbolic links are stored in the inode, 166and directories have an added field showing the file type. 167.It 3 168If maxcontig is greater than one, 169build the free segment maps to aid in finding contiguous sets of blocks. 170If maxcontig is equal to one, delete any existing segment maps. 171.El 172.Pp 173In interactive mode, 174.Nm fsck 175will list the conversion to be made 176and ask whether the conversion should be done. 177If a negative answer is given, 178no further operations are done on the filesystem. 179In preen mode, 180the conversion is listed and done if 181possible without user interaction. 182Conversion in preen mode is best used when all the filesystems 183are being converted at once. 184The format of a filesystem can be determined from the 185first line of output from 186.Xr dumpfs 8 . 187.El 188.Pp 189If no filesystems are given to 190.Nm fsck 191then a default list of filesystems is read from 192the file 193.Pa /etc/fstab . 194.Pp 195.Bl -enum -indent indent -compact 196Inconsistencies checked are as follows: 197.It 198Blocks claimed by more than one inode or the free map. 199.It 200Blocks claimed by an inode outside the range of the filesystem. 201.It 202Incorrect link counts. 203.It 204Size checks: 205.Bl -item -indent indent -compact 206.It 207Directory size not a multiple of DIRBLKSIZ. 208.It 209Partially truncated file. 210.El 211.It 212Bad inode format. 213.It 214Blocks not accounted for anywhere. 215.It 216Directory checks: 217.Bl -item -indent indent -compact 218.It 219File pointing to unallocated inode. 220.It 221Inode number out of range. 222.It 223Dot or dot-dot not the first two entries of a directory 224or having the wrong inode number. 225.El 226.It 227Super Block checks: 228.Bl -item -indent indent -compact 229.It 230More blocks for inodes than there are in the filesystem. 231.It 232Bad free block map format. 233.It 234Total free block and/or free inode count incorrect. 235.El 236.El 237.Pp 238Orphaned files and directories (allocated but unreferenced) are, 239with the operator's concurrence, reconnected by 240placing them in the 241.Pa lost+found 242directory. 243The name assigned is the inode number. 244If the 245.Pa lost+found 246directory does not exist, it is created. 247If there is insufficient space its size is increased. 248.Pp 249Because of inconsistencies between the block device and the buffer cache, 250the raw device should always be used. 251.Sh FILES 252.Bl -tag -width /etc/fstab -compact 253.It Pa /etc/fstab 254contains default list of filesystems to check. 255.El 256.Sh DIAGNOSTICS 257The diagnostics produced by 258.Nm fsck 259are fully enumerated and explained in Appendix A of 260.Rs 261.%T "Fsck \- The UNIX File System Check Program" 262.Re 263.Sh SEE ALSO 264.Xr fstab 5 , 265.Xr fs 5 , 266.Xr fsdb 8 , 267.Xr newfs 8 , 268.Xr mkfs 8 , 269.Xr reboot 8 270