1.\" Copyright (c) 1980, 1989, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)fsck.8 6.10 (Berkeley) 07/12/92 7.\" 8.Dd 9.Dt FSCK 8 10.Os BSD 4 11.Sh NAME 12.Nm fsck 13.Nd file system 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 21.Op Fl y 22.Op Fl n 23.Op Fl m Ar mode 24.Op Ar filesystem 25.Ar ... 26.Sh DESCRIPTION 27The first form of 28.Nm fsck 29preens a standard set of filesystems or the specified file systems. 30It is normally used in the script 31.Pa /etc/rc 32during automatic reboot. 33Here 34.Nm fsck 35reads the table 36.Pa /etc/fstab 37to determine which file systems to check. 38Only partitions in fstab that are mounted ``rw,'' ``rq'' or ``ro'' 39and that have non-zero pass number are checked. 40Filesystems with pass number 1 (normally just the root filesystem) 41are checked one at a time. 42When pass 1 completes, all remaining filesystems are checked, 43running one process per disk drive. 44The disk drive containing each filesystem is inferred from the longest prefix 45of the device name that ends in a digit; the remaining characters are assumed 46to be the partition designator. 47.Pp 48The system takes care that only a restricted class of innocuous 49inconsistencies can happen unless hardware or software failures intervene. 50These are limited to the following: 51.Bl -item -compact -indent indent 52.It Unreferenced inodes 53.It Link counts in inodes too large 54.It Missing blocks in the free map 55.It Blocks in the free map also in files 56.It Counts in the super-block wrong 57.El 58.Pp 59These are the only inconsistencies that 60.Nm fsck 61with the 62.Fl p 63option will correct; if it encounters other inconsistencies, it exits 64with an abnormal return status and an automatic reboot will then fail. 65For each corrected inconsistency one or more lines will be printed 66identifying the file system on which the correction will take place, 67and the nature of the correction. After successfully correcting a file 68system, 69.Nm fsck 70will print the number of files on that file system, 71the number of used and free blocks, 72and the percentage of fragmentation. 73.Pp 74If sent a 75.Dv QUIT 76signal, 77.Nm fsck 78will finish the file system checks, then exit with an abnormal 79return status that causes an automatic reboot to fail. 80This is useful when to finish the file system checks during an automatic reboot, 81but do not want the machine to come up multiuser after the checks complete. 82.Pp 83Without the 84.Fl p 85option, 86.Nm fsck 87audits and interactively repairs inconsistent conditions for file systems. 88If the file system is inconsistent the operator is prompted for concurrence 89before each correction is attempted. 90It should be noted that some of the corrective actions which are not 91correctable under the 92.Fl p 93option will result in some loss of data. 94The amount and severity of data lost may be determined from the diagnostic 95output. 96The default action for each consistency correction 97is to wait for the operator to respond 98.Li yes 99or 100.Li no . 101If the operator does not have write permission on the file system 102.Nm fsck 103will default to a 104.Fl n 105action. 106.Pp 107.Nm Fsck 108has more consistency checks than 109its predecessors 110.Em check , dcheck , fcheck , 111and 112.Em icheck 113combined. 114.Pp 115The following flags are interpreted by 116.Nm fsck . 117.Bl -tag -width indent 118.It Fl b 119Use the block specified immediately after the flag as 120the super block for the file system. Block 32 is usually 121an alternate super block. 122.It Fl l 123Limit the number of parallel checks to the number specified in the following 124argument. 125By default, the limit is the number of disks, running one process per disk. 126If a smaller limit is given, the disks are checked round-robin, one filesystem 127at a time. 128.It Fl m 129Use the mode specified in octal immediately after the flag as the 130permission bits to use when creating the 131.Pa lost+found 132directory rather than the default 1777. 133In particular, systems that do not wish to have lost files accessible 134by all users on the system should use a more restrictive 135set of permissions such as 700. 136.It Fl y 137Assume a yes response to all questions asked by 138.Nm fsck ; 139this should be used with great caution as this is a free license 140to continue after essentially unlimited trouble has been encountered. 141.It Fl n 142Assume a no response to all questions asked by 143.Nm fsck 144except for 145.Ql CONTINUE? , 146which is assumed to be affirmative; 147do not open the file system for writing. 148.It Fl c 149If the file system is in the old (static table) format, 150convert it to the new (dynamic table) format. 151If the file system is in the new format, 152convert it to the old format provided the old format 153can support the filesystem configuration. 154In interactive mode, 155.Nm fsck 156will list the direction the conversion is to be made 157and ask whether the conversion should be done. 158If a negative answer is given, 159no further operations are done on the filesystem. 160In preen mode, 161the direction of the conversion is listed and done if 162possible without user interaction. 163Conversion in preen mode is best used when all the file systems 164are being converted at once. 165The format of a file system can be determined from the 166first line of output from 167.Xr dumpfs 8 . 168.El 169.Pp 170If no filesystems are given to 171.Nm fsck 172then a default list of file systems is read from 173the file 174.Pa /etc/fstab . 175.Pp 176.Bl -enum -indent indent -compact 177Inconsistencies checked are as follows: 178.It 179Blocks claimed by more than one inode or the free map. 180.It 181Blocks claimed by an inode outside the range of the file system. 182.It 183Incorrect link counts. 184.It 185Size checks: 186.Bl -item -indent indent -compact 187.It 188Directory size not of proper format. 189.It 190Partially truncated file. 191.El 192.It 193Bad inode format. 194.It 195Blocks not accounted for anywhere. 196.It 197Directory checks: 198.Bl -item -indent indent -compact 199.It 200File pointing to unallocated inode. 201.It 202Inode number out of range. 203.It 204Dot or dot-dot not the first two entries of a directory 205or having the wrong inode number. 206.El 207.It 208Super Block checks: 209.It 210More blocks for inodes than there are in the file system. 211.It 212Bad free block map format. 213.It 214Total free block and/or free inode count incorrect. 215.El 216.Pp 217Orphaned files and directories (allocated but unreferenced) are, 218with the operator's concurrence, reconnected by 219placing them in the 220.Pa lost+found 221directory. 222The name assigned is the inode number. 223If the 224.Pa lost+found 225directory does not exist, it is created. 226If there is insufficient space its size is increased. 227.Pp 228Because of inconsistencies between the block device and the buffer cache, 229the raw device should always be used. 230.Sh FILES 231.Bl -tag -width /etc/fstab -compact 232.It Pa /etc/fstab 233contains default list of file systems to check. 234.El 235.Sh DIAGNOSTICS 236The diagnostics produced by 237.Nm fsck 238are fully enumerated and explained in Appendix A of 239.Rs 240.%T "Fsck \- The UNIX File System Check Program" 241.Re 242.Sh SEE ALSO 243.Xr fstab 5 , 244.Xr fs 5 , 245.Xr fsdb 8 , 246.Xr newfs 8 , 247.Xr mkfs 8 , 248.Xr reboot 8 249