diff options
Diffstat (limited to 'man/chmod.x')
| -rw-r--r-- | man/chmod.x | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/man/chmod.x b/man/chmod.x index 9a73cd5..5761d36 100644 --- a/man/chmod.x +++ b/man/chmod.x @@ -1,4 +1,4 @@ -'\" Copyright (C) 1998, 1999, 2001, 2006 Free Software Foundation, Inc. +'\" Copyright (C) 1998-2016 Free Software Foundation, Inc. '\" '\" This is free software. You may redistribute copies of it under the terms '\" of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. @@ -16,7 +16,7 @@ which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new mode bits. .PP The format of a symbolic mode is [\c -\fBugoa\fP.\|.\|.][[\fB+-=\fP][\fIperms\fP.\|.\|.].\|.\|.], +\fBugoa\fP.\|.\|.][[\fB-+=\fP][\fIperms\fP.\|.\|.].\|.\|.], where .I "perms" is either zero or more letters from the set @@ -28,7 +28,7 @@ A combination of the letters \fBugoa\fP controls which users' access to the file will be changed: the user who owns it (\fBu\fP), other users in the file's group (\fBg\fP), other users not in the file's group (\fBo\fP), or all users (\fBa\fP). If none of these are given, -the effect is as if \fBa\fP were +the effect is as if (\fBa\fP) were given, but bits that are set in the umask are not affected. .PP The operator \fB+\fP causes the selected file mode bits to be added to @@ -51,8 +51,7 @@ categories (\fBo\fP). .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. Omitted digits are -assumed to be leading zeros, except that if the first digit is -omitted, a directory's set user and group ID bits are not affected. +assumed to be leading zeros. The first digit selects the set user ID (4) and set group ID (2) and restricted deletion or sticky (1) attributes. The second digit selects permissions for the user who owns the file: read (4), write (2), @@ -72,6 +71,30 @@ In contrast, .B chmod ignores symbolic links encountered during recursive directory traversals. +.SH "SETUID AND SETGID BITS" +.B chmod +clears the set-group-ID bit of a +regular file if the file's group ID does not match the user's +effective group ID or one of the user's supplementary group IDs, +unless the user has appropriate privileges. Additional restrictions +may cause the set-user-ID and set-group-ID bits of +.I MODE +or +.I RFILE +to be ignored. This behavior depends on the policy and +functionality of the underlying +.B chmod +system call. When in +doubt, check the underlying system behavior. +.PP +.B chmod +preserves a directory's set-user-ID and set-group-ID bits unless you +explicitly specify otherwise. You can set or clear the bits with +symbolic modes like +.B u+s +and +.BR g\-s , +and you can set (but not clear) the bits with a numeric mode. .SH "RESTRICTED DELETION FLAG OR STICKY BIT" The restricted deletion flag or sticky bit is a single bit, whose interpretation depends on the file type. For directories, it prevents |