| 1 | .TH CHMOD 1 |
| 2 | .SH NAME |
| 3 | chmod \- change mode |
| 4 | .SH SYNOPSIS |
| 5 | .B chmod |
| 6 | mode file ... |
| 7 | .SH DESCRIPTION |
| 8 | The mode of |
| 9 | each named file |
| 10 | is changed |
| 11 | according to |
| 12 | .I mode, |
| 13 | which may be absolute or symbolic. |
| 14 | An absolute |
| 15 | .I mode |
| 16 | is an octal |
| 17 | number constructed |
| 18 | from the OR of the |
| 19 | following modes: |
| 20 | .TP 10 |
| 21 | 4000 |
| 22 | set user ID on execution |
| 23 | .br |
| 24 | .br |
| 25 | .ns |
| 26 | .TP 10 |
| 27 | 2000 |
| 28 | set group ID on execution |
| 29 | .br |
| 30 | .br |
| 31 | .ns |
| 32 | .TP 10 |
| 33 | 1000 |
| 34 | sticky bit, see |
| 35 | .IR chmod (2) |
| 36 | .br |
| 37 | .br |
| 38 | .ns |
| 39 | .TP 10 |
| 40 | 0400 |
| 41 | read by owner |
| 42 | .br |
| 43 | .br |
| 44 | .ns |
| 45 | .TP 10 |
| 46 | 0200 |
| 47 | write by owner |
| 48 | .br |
| 49 | .br |
| 50 | .ns |
| 51 | .TP 10 |
| 52 | 0100 |
| 53 | execute (search in directory) by owner |
| 54 | .br |
| 55 | .br |
| 56 | .ns |
| 57 | .TP 10 |
| 58 | 0070 |
| 59 | read, write, execute (search) by group |
| 60 | .br |
| 61 | .br |
| 62 | .ns |
| 63 | .TP 10 |
| 64 | 0007 |
| 65 | read, write, execute (search) by others |
| 66 | .PP |
| 67 | A symbolic |
| 68 | .I mode |
| 69 | has the form: |
| 70 | .IP |
| 71 | .RI [ who ] |
| 72 | .I op permission |
| 73 | .RI [ "op permission" "] ..." |
| 74 | .PP |
| 75 | The |
| 76 | .I who |
| 77 | part is a combination |
| 78 | of the letters |
| 79 | .B u |
| 80 | (for user's permissions), |
| 81 | .B g |
| 82 | (group) |
| 83 | and |
| 84 | .B o |
| 85 | (other). |
| 86 | The letter |
| 87 | .B a |
| 88 | stands for |
| 89 | .B ugo. |
| 90 | If |
| 91 | .I who |
| 92 | is omitted, |
| 93 | the default is |
| 94 | .I a |
| 95 | but the setting of |
| 96 | the file creation mask |
| 97 | (see umask(2)) |
| 98 | is taken into account. |
| 99 | .PP |
| 100 | .I Op |
| 101 | can be |
| 102 | .B + |
| 103 | to add |
| 104 | .I permission |
| 105 | to the file's mode, |
| 106 | .B \- |
| 107 | to take away |
| 108 | .I permission |
| 109 | and |
| 110 | .B = |
| 111 | to assign |
| 112 | .I permission |
| 113 | absolutely |
| 114 | (all other bits will |
| 115 | be reset). |
| 116 | .PP |
| 117 | .I Permission |
| 118 | is any combination of the letters |
| 119 | .B r |
| 120 | (read), |
| 121 | .B w |
| 122 | (write), |
| 123 | .B x |
| 124 | (execute), |
| 125 | .B s |
| 126 | (set owner or group id) |
| 127 | and |
| 128 | .B t |
| 129 | (save text \- sticky). |
| 130 | Letters |
| 131 | .BR u, |
| 132 | .B g |
| 133 | or |
| 134 | .B o |
| 135 | indicate that |
| 136 | .I permission |
| 137 | is to be taken |
| 138 | from the current |
| 139 | mode. |
| 140 | Omitting |
| 141 | .I permission |
| 142 | is only useful |
| 143 | with |
| 144 | .B = |
| 145 | to take away |
| 146 | all permissions. |
| 147 | .PP |
| 148 | The first example denies write permission to others, |
| 149 | the second makes a file executable: |
| 150 | .IP |
| 151 | chmod o\-w file |
| 152 | .br |
| 153 | chmod +x file |
| 154 | .PP |
| 155 | Multiple symbolic modes separated by commas may be given. |
| 156 | Operations are performed |
| 157 | in the order specified. |
| 158 | The letter |
| 159 | .B s |
| 160 | is only useful |
| 161 | with |
| 162 | .B u |
| 163 | or |
| 164 | .B g. |
| 165 | .PP |
| 166 | Only the owner of a file (or the super-user) may change its mode. |
| 167 | .SH "SEE ALSO" |
| 168 | ls(1), |
| 169 | chmod(2), |
| 170 | chown (1), |
| 171 | stat(2), |
| 172 | umask(2) |