diff options
| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2004-11-03 13:51:07 +0000 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2004-11-03 13:51:07 +0000 |
| commit | fea681dafb1363a154b7fc6d59baa83d2a9ebc5c (patch) | |
| tree | 8ea275c0f242af739617d0afc3e1b16c4eff3dc2 /man1/chmod.1 | |
| download | man-pages-fea681dafb1363a154b7fc6d59baa83d2a9ebc5c.tar.gz | |
Import of man-pages 1.70man-pages-1.70
Diffstat (limited to 'man1/chmod.1')
| -rw-r--r-- | man1/chmod.1 | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/man1/chmod.1 b/man1/chmod.1 new file mode 100644 index 0000000000..4f047aad70 --- /dev/null +++ b/man1/chmod.1 @@ -0,0 +1,160 @@ +.\" Copyright Andries Brouwer, Ragnar Hojland Espinosa and A. Wik, 1998. +.\" +.\" This file may be copied under the conditions described +.\" in the LDP GENERAL PUBLIC LICENSE, Version 1, September 1998 +.\" that should have been distributed together with this file. +.\" +.\" Modified 2004-06-17, Michael Kerrisk +.\" +.TH CHMOD 1 2004-06-17 "GNU fileutils 4.0" +.SH NAME +chmod \- change access permissions of files +.SH SYNOPSIS +.BI "chmod [" options "] " "mode file..." +.sp +POSIX options: +.B "[\-R] [\-\-]" +.sp +GNU mode denotation: +.BI [\-\-reference= rfile ] +.sp +GNU options (shortest form): +.B [\-cfvR] +.B "[\-\-help] [\-\-version] [\-\-]" +.SH DESCRIPTION +.B chmod +changes the permissions of each given +.I file +according to +.IR mode , +which can be either a symbolic representation of changes to make, or +an octal number representing the bit pattern for the new permissions. +.PP +The format of a symbolic mode change argument is +.br +\&`[ugoa...][[+\-=][rwxXstugo...]...][,...]'. +.PP +Such an argument is a list of symbolic mode change commands, +separated by commas. +Each symbolic mode change command starts with zero or more +of the letters `ugoa'; these control which users' access to +the file will be changed: the user who owns it (u), other users in the +file's group (g), other users not in the file's group (o), or all +users (a). Thus, `a' is here equivalent to `ugo'. +If none of these are given, the effect is as if `a' were +given, but bits that are set in the umask are not affected. +.PP +The operator `+' causes the permissions selected to be added to the +existing permissions of each file; `\-' causes them to be removed; +and `=' causes them to be the only permissions that the file has. +.PP +The letters `rwxXstugo' select the new permissions for the affected +users: read (r), write (w), execute (or access for directories) (x), +execute only if the file is a directory or already has execute +permission for some user (X), set user or group ID on execution (s), +sticky bit (t), the permissions that the user +who owns the file currently has for it (u), the permissions that other +users in the file's group have for it (g), and the permissions that +other users not in the file's group have for it (o). +(Thus, `chmod g\-s file' removes the set-group-ID (sgid) bit, +\&`chmod ug+s file' sets both the suid and sgid bits, while +\&`chmod o+s file' does nothing.) +.PP +The name of the `sticky bit' derives from the original meaning: +keep program text on swap device. +These days, when set for a directory, it means that +only the owner of the file and the owner of that directory +may remove the file from that directory. +(This is commonly used on directories like /tmp that have +general write permission.) +.PP +A numeric mode is from one to four octal digits (0-7), derived by +adding up the bits with values 4, 2, and 1. Any omitted digits are +assumed to be leading zeros. The first digit selects the set user ID +(4) and set group ID (2) and save text image [`sticky'] (1) attributes. +The second digit selects permissions for the user who owns the file: read +(4), write (2), and execute (1); the third selects permissions for +other users in the file's group, with the same values; and the fourth +for other users not in the file's group, with the same values. +.PP +.B chmod +never changes the permissions of symbolic links, since the +.B chmod +system call cannot change their permissions. This is not a problem +since the permissions of symbolic links are never used. However, for +each symbolic link listed on the command line, +.B chmod +changes the permissions of the pointed-to file. In contrast, +.B chmod +ignores symbolic links encountered during recursive directory traversals. +.SH "POSIX OPTIONS" +.TP +.B "\-R" +Recursively change permissions of directories and their contents. +.TP +.B "\-\-" +Terminate option list. +.SH "ADDITIONAL GNU DESCRIPTION" +A GNU extension (new in fileutils 4.0) allows one to use +.BI "\-\-reference=" "rfile" +as a mode description: the same mode as that of +.IR rfile . +.SH "GNU OPTIONS" +.TP +.B "\-c, \-\-changes" +Verbosely describe the action for each +.I file +whose permissions actually changes. +.TP +.B "\-f, \-\-silent, \-\-quiet" +Do not print error messages about files whose permissions cannot be changed. +.TP +.B "\-v, \-\-verbose" +Verbosely describe the action or non-action taken for every +.IR file . +.TP +.B "\-R, \-\-recursive" +Recursively change permissions of directories and their contents. +.SH "GNU STANDARD OPTIONS" +.TP +.B "\-\-help" +Print a usage message on standard output and exit successfully. +.TP +.B "\-\-version" +Print version information on standard output, then exit successfully. +.TP +.B "\-\-" +Terminate option list. +.SH ENVIRONMENT +The variables LANG, LC_ALL, LC_CTYPE and LC_MESSAGES have the +usual meaning. For an XSI-conforming system: NLSPATH has the +usual meaning. +.SH "CONFORMING TO" +POSIX 1003.2 only requires the \-R option. Use of other options +may not be portable. This standard does not describe the 't' permission +bit. This standard does not specify whether \fBchmod\fP must preserve +consistency by clearing or refusing to set the suid and sgid +bits, e.g., when all execute bits are cleared, or whether \fBchmod\fP +honors the `s' bit at all. +.SH "NONSTANDARD MODES" +Above we described the use of the `t' bit on directories. +Various systems attach special meanings to otherwise +meaningless combinations of mode bits. +In particular, Linux, following System V (see +System V Interface Definition (SVID) Version 3), +lets the sgid bit for files without group execute permission +mark the file for mandatory locking. For more details, see +the file +.IR /usr/src/linux/Documentation/mandatory.txt . +.SH NOTES +This page describes +.B chmod +as found in the fileutils-4.0 package; +other versions may differ slightly. +.SH "SEE ALSO" +.BR chattr (1), +.BR chown (1), +.BR install (1), +.BR chmod (2), +.BR stat (2), +.BR umask (2) |