1.\" Copyright (c) 1989, 1990 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)chmod.1 6.12 (Berkeley) 01/09/91 7.\" 8.Dd 9.Dt CHMOD 1 10.Os BSD 4.4 11.Sh NAME 12.Nm chmod 13change file modes 14.Sh SYNOPSIS 15.Nm chmod 16.Op Fl fR 17.Ar mode 18.Ar file ... 19.Sh DESCRIPTION 20The 21.Nm chmod 22utility modifies the file mode bits of the listed files 23as specified by the 24.Ar mode 25operand. 26.Pp 27The options are as follows: 28.Tw Ds 29.Tp Fl f 30.Nm chmod 31will still exit 0 and not complain if it fails to change the mode 32on a file. 33.Tp Fl R 34Traverse a file hierarchy. 35For each file that is of type directory, 36.Nm chmod 37changes the mode of all files in the file hierarchy below it followed 38by the mode of the directory itself. 39.Tp 40.Pp 41Symbolic links are not indirected through, nor are their modes altered. 42.Pp 43Only the owner of a file or the super-user is permitted to change 44the mode of a file. 45.Pp 46The 47.Nm chmod 48utility exits 0 on success, and >0 if an error occurs. 49.Sh MODES 50Modes may be absolute or symbolic. 51An absolute mode is an octal number constructed by 52.Cx Ar or 53.Cx 'ing 54.Cx 55the following values: 56.Df I 57.Dw Fl 58.Dp Li 4000 59set-user-ID-on-execution 60.Dp Li 2000 61set-group-ID-on-execution 62.Dp Li 1000 63sticky bit, see chmod(2) 64.Dp Li 0400 65read by owner 66.Dp Li 0200 67write by owner 68.Dp Li 0100 69execute (or search for directories) by owner 70.Dp Li 0070 71read, write, execute/search by group 72.Dp Li 0007 73read, write, execute/search by others 74.Dp 75.De 76.Pp 77The read, write, and execute/search values for group and others 78are encoded as described for owner. 79.Pp 80The symbolic mode is described by the following grammar: 81.Dp Li mode 82::= clause 83.Op \&, clause 84... 85.Dp Li clause 86::= 87.Op who ... 88.Op action ... 89last_action 90.Dp Li action 91::= op perm ... 92.Dp Li last_action 93::= op 94.Op perm ... 95.Dp Li who 96.Li ::= a | u | g | o 97.Dp Li op 98.Li ::= + | - | = 99.Dp Li perm 100.Li ::= r | s | t | w | X | x | u | g | o 101.Dp 102.Pp 103The 104.Ar who 105symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts 106of the mode bits, respectively. 107The 108.Ar who 109symbol ``a'' is equivalent to ``ugo''. 110.Pp 111The 112.Ar perm 113symbols represent the portions of the mode bits as follows: 114.Dw Ds 115.Dp r 116The read bits. 117.Dp s 118The set-user-ID-on-execution and set-group-ID-on-execution bits. 119.Dp t 120The sticky bit. 121.Dp w 122The write bits. 123.Dp x 124The execute/search bits. 125.Dp X 126The execute/search bits if the file is a directory or any of the 127execute/search bits are set in the original (unmodified) mode. 128Operations with the 129.Ar perm 130symbol ``X'' are only meaningful in conjunction with the 131.Ar op 132symbol ``+'', and it is ignored in all other cases. 133.Dp 134.Pp 135The 136.Ar op 137symbols represent the operation performed, as follows: 138.Tw Ds 139.Tp \&+ 140If no value is supplied for 141.Ar perm , 142the ``+'' operation has no effect. 143If no value is supplied for 144.Ar who , 145each permission bit specified in 146.Ar perm , 147for which the corresponding bit in the file mode creation mask 148is clear, is set. 149Otherwise, the mode bits represented by the specified 150.Ar who 151and 152.Ar perm 153values are set. 154.Tp \&- 155If no value is supplied for 156.Ar perm , 157the ``-'' operation has no effect. 158If no value is supplied for 159.Ar who , 160the mode bits represented by 161.Ar perm 162are cleared for the owner, group and other permissions. 163Otherwise, the mode bits represented by the specified 164.Ar who 165and 166.Ar perm 167values are cleared. 168.Tp \&= 169The mode bits specified by the 170.Ar who 171value are cleared, or, if no who value is specified, the owner, group 172and other mode bits are cleared. 173Then, if no value is supplied for 174.Ar who , 175each permission bit specified in 176.Ar perm , 177for which the corresponding bit in the file mode creation mask 178is clear, is set. 179Otherwise, the mode bits represented by the specified 180.Ar who 181and 182.Ar perm 183values are set. 184.Tp 185.Pp 186Each 187.Ar clause 188specifies one or more operations to be performed on the mode 189bits, and each operation is applied to the mode bits in the 190order specified. 191.Pp 192Operations upon the other permissions only (specified by the symbol 193``o'' by itself), in combination with the 194.Ar perm 195symbols ``s'' or ``t'', are ignored. 196.Sh EXAMPLES 197.Tw Ar 198.Tp ``644'' 199make a file readable by anyone and writable by the owner only. 200.Tp ``go-w'' 201deny write permission to group and others. 202.Tp ``=rw,+X'' 203set the read and write permissions to the usual defaults, but 204retain any execute permissions that are currently set. 205.Tp ``+X'' 206make a directory or file searchable/executable by everyone if it is 207already searchable/executable by anyone. 208.Tp ``755'', ``u=rwx,go=rx'' or ``u=rwx,go=u-w'' 209make a file readable/executable by everyone and writeable by the owner only. 210.Tp ``go='' 211clear all mode bits for group and others. 212.Tp ``g=u-w'' 213set the group bits equal to the user bits, but clear the group write bit. 214.Tp 215.Sh BUGS 216There's no 217.Ar perm 218option for the naughty bits. 219.Sh SEE ALSO 220.Xr install 1 , 221.Xr chmod 2 , 222.Xr stat 2 , 223.Xr umask 2 , 224.Xr fts 3 , 225.Xr setmode 3 , 226.Xr chown 8 227.Sh STANDARDS 228The 229.Nm chmod 230utility is expected to be POSIX 1003.2 compatible with the exception 231of the 232.Ar perm 233symbols ``t'' and ``X'' which are not included in that standard. 234