Man ÇÏ×ÏÒÉÔ:
"... The letters 'rwxXstugo' ...
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 execute (s) ..."
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>Man ÇÏ×ÏÒÉÔ:
>"... The letters 'rwxXstugo' ...
>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
>execute (s) ..."
>ï S - ÎÉ ÓÌÏ×Á, ÓÌÅÄÕÅÔ
>ÌÉ ÐÏÌÁÇÁÔØ, ÞÔÏ S ÎÅÓÅÔ
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>X, É s ?
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>?
>man chmod - ÒÅÖÉÍ 4000
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É ËÁË ÐÒÏÓÔÏÊ ÓÍÅÒÔÎÙÊ ÄÏÌÖÅÎ ÄÏÇÁÄÁÔØÓÑ ÞÔÏ ÜÔÏ s ÍÁÌÅÎØËÏÅ?chmod (1)
chmod - change access permissions of filesSYNOPSIS
chmod [options] mode file...
POSIX options: [-R]
GNU options (shortest form): [-cfvR] [--help] [--version]
[--]DESCRIPTION
chmod changes the permissions of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number representing the bit
pattern for the new permissions.The format of a symbolic mode change argument is
`[ugoa...][[+-=][rwxXstugo...]...][,...]'.Such an argument is a list of symbolic mode change com
mands, 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.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.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 direc
tory 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.)The `sticky bit' is not described by POSIX. The name
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
general write permission.)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.chmod never changes the permissions of symbolic links,
since the chmod system call cannot change their permis
sions. This is not a problem since the permissions of
symbolic links are never used. However, for each symbolic
link listed on the command line, chmod changes the permis
sions of the pointed-to file. In contrast, chmod ignores
symbolic links encountered during recursive directory
traversals.POSIX OPTIONS
-R Recursively change permissions of directories and
their contents.GNU OPTIONS
-c, --changes
Verbosely describe the action for each file whose
permissions actually changes.-f, --silent, --quiet
Do not print error messages about files whose per
missions cannot bechanged.-v, --verbose
Verbosely describe the action or non-action taken
for every file.-R, --recursive
Recursively change permissions of directories and
their contents.GNU STANDARD OPTIONS
--help Print a usage message on standard output and exit
successfully.--version
Print version information on standard output, then
exit successfully.-- Terminate option list.
The variables LANG, LC_ALL, LC_CTYPE and LC_MESSAGES have
the usual meaning.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 chmod must preserve consistency by clear
ing or refusing to set the suid and sgid bits, e.g., when
all execute bits are cleared, or whether chmod honors the
`s' bit at all.NONSTANDARD MODES
Above we described the use of the `t' bit on directories.
Various systems attach special meanings to otherwise mean
ingless 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 lock
ing. For more details, see the file /usr/src/linux/Docu
mentation/mandatory.txt.NOTES
This page describes chmod as found in the fileutils-3.16
package; other versions may differ slightly. Mail correc
tions and additions to aeb@cwi.nl, aw@mail1.bet1.puv.fi
and ragnar@lightside.ddns.org. Report bugs in the program
to fileutils-bugs@gnu.ai.mit.edu.
åÌËÉ, ÏÈ ÕÖ ÜÔÏÔ Linux, ÇÎÕÔÙÊ chmod, ÔÏÞÎÅÅ
ÏÐÉÓÁÎÉÅ ÉÚ GNU, ÎÉÖÅ ÉÚ BSD:MODES
Modes may be absolute or symbolic. An absolute mode is an octal number
constructed from the sum of one or more of the following values:4000 (the set-user-ID-on-execution bit) Executable files with
this bit set will run with effective uid set to the uid of
the file owner. Directories with the set-user-id bit set
will force all files and sub-directories created in them to
be owned by the directory owner and not by the uid of the
creating process, if the underlying file system supports
this feature: see chmod(2) and the suiddir option to
mount(8).
2000 (the set-group-ID-on-execution bit) Executable files with
this bit set will run with effective gid set to the gid of
the file owner.
1000 (the sticky bit) When set on a directory, unprivileged
users can delete and rename only those files in the direc-
tory that are owned by them, regardless of the permissions
on the directory. Under FreeBSD, the sticky bit is ignored
for executable files and may only be set for directories
(see sticky(8)).
0400 Allow read by owner.
0200 Allow write by owner.
0100 For files, allow execution by owner. For directories, al-
low the owner to search in the directory.
0040 Allow read by group members.
0020 Allow write by group members.
0010 For files, allow execution by group members. For directo-
ries, allow group members to search in the directory.
0004 Allow read by others.
0002 Allow write by others.
0001 For files, allow execution by others. For directories al-
low others to search in the directory.