diff options
Diffstat (limited to 'coreutils-5.3.0-bin/man/cat1p/chmod.1p.txt')
| -rw-r--r-- | coreutils-5.3.0-bin/man/cat1p/chmod.1p.txt | 462 |
1 files changed, 462 insertions, 0 deletions
diff --git a/coreutils-5.3.0-bin/man/cat1p/chmod.1p.txt b/coreutils-5.3.0-bin/man/cat1p/chmod.1p.txt new file mode 100644 index 0000000..fcc36ee --- /dev/null +++ b/coreutils-5.3.0-bin/man/cat1p/chmod.1p.txt @@ -0,0 +1,462 @@ +chmod(P) chmod(P) + + + + + +NAME + chmod - change the file modes + +SYNOPSIS + chmod [-R] mode file ... + +DESCRIPTION + The chmod utility shall change any or all of the file + mode bits of the file named by each file operand in the + way specified by the mode operand. + + It is implementation-defined whether and how the chmod + utility affects any alternate or additional file access + control mechanism (see the Base Definitions volume of + IEEE Std 1003.1-2001, Section 4.4, File Access Permis- + sions) being used for the specified file. + + Only a process whose effective user ID matches the user + ID of the file, or a process with the appropriate privi- + leges, shall be permitted to change the file mode bits + of a file. + +OPTIONS + The chmod utility shall conform to the Base Definitions + volume of IEEE Std 1003.1-2001, Section 12.2, Utility + Syntax Guidelines. + + The following option shall be supported: + + -R Recursively change file mode bits. For each file + operand that names a directory, chmod shall + change the file mode bits of the directory and + all files in the file hierarchy below it. + + +OPERANDS + The following operands shall be supported: + + mode Represents the change to be made to the file mode + bits of each file named by one of the file oper- + ands; see the EXTENDED DESCRIPTION section. + + file A pathname of a file whose file mode bits shall + be modified. + + +STDIN + Not used. + +INPUT FILES + None. + +ENVIRONMENT VARIABLES + The following environment variables shall affect the + execution of chmod: + + LANG Provide a default value for the internationaliza- + tion variables that are unset or null. (See the + Base Definitions volume of IEEE Std 1003.1-2001, + Section 8.2, Internationalization Variables for + the precedence of internationalization variables + used to determine the values of locale cate- + gories.) + + LC_ALL If set to a non-empty string value, override the + values of all the other internationalization + variables. + + LC_CTYPE + Determine the locale for the interpretation of + sequences of bytes of text data as characters + (for example, single-byte as opposed to multi- + byte characters in arguments). + + LC_MESSAGES + Determine the locale that should be used to + affect the format and contents of diagnostic mes- + sages written to standard error. + + NLSPATH + Determine the location of message catalogs for + the processing of LC_MESSAGES . + + +ASYNCHRONOUS EVENTS + Default. + +STDOUT + Not used. + +STDERR + The standard error shall be used only for diagnostic + messages. + +OUTPUT FILES + None. + +EXTENDED DESCRIPTION + The mode operand shall be either a symbolic_mode expres- + sion or a non-negative octal integer. The symbolic_mode + form is described by the grammar later in this section. + + Each clause shall specify an operation to be performed + on the current file mode bits of each file. The opera- + tions shall be performed on each file in the order in + which the clauses are specified. + + The who symbols u, g, and o shall specify the user, + group, and other parts of the file mode bits, respec- + tively. A who consisting of the symbol a shall be equiv- + alent to ugo. + + The perm symbols r, w, and x represent the read, write, + and execute/ search portions of file mode bits, respec- + tively. The perm symbol s shall represent the set-user- + ID-on-execution (when who contains or implies u) and + set-group-ID-on-execution (when who contains or implies + g) bits. + + The perm symbol X shall represent the execute/search + portion of the file mode bits if the file is a directory + or if the current (unmodified) file mode bits have at + least one of the execute bits (S_IXUSR, S_IXGRP, or + S_IXOTH) set. It shall be ignored if the file is not a + directory and none of the execute bits are set in the + current file mode bits. + + The permcopy symbols u, g, and o shall represent the + current permissions associated with the user, group, and + other parts of the file mode bits, respectively. For the + remainder of this section, perm refers to the non-termi- + nals perm and permcopy in the grammar. + + If multiple actionlists are grouped with a single + wholist in the grammar, each actionlist shall be applied + in the order specified with that wholist. The op symbols + shall represent the operation performed, as follows: + + + If perm is not specified, the '+' operation shall + not change the file mode bits. + + If who is not specified, the file mode bits represented + by perm for the owner, group, and other permissions, + except for those with corresponding bits in the file + mode creation mask of the invoking process, shall be + set. + + Otherwise, the file mode bits represented by the speci- + fied who and perm values shall be set. + + - If perm is not specified, the '-' operation shall + not change the file mode bits. + + If who is not specified, the file mode bits represented + by perm for the owner, group, and other permissions, + except for those with corresponding bits in the file + mode creation mask of the invoking process, shall be + cleared. + + Otherwise, the file mode bits represented by the speci- + fied who and perm values shall be cleared. + + = Clear the file mode bits specified by the who + value, or, if no who value is specified, all of + the file mode bits specified in this volume of + IEEE Std 1003.1-2001. + + If perm is not specified, the '=' operation shall make + no further modifications to the file mode bits. + + If who is not specified, the file mode bits represented + by perm for the owner, group, and other permissions, + except for those with corresponding bits in the file + mode creation mask of the invoking process, shall be + set. + + Otherwise, the file mode bits represented by the speci- + fied who and perm values shall be set. + + + When using the symbolic mode form on a regular file, it + is implementation-defined whether or not: + + Requests to set the set-user-ID-on-execution or + set-group-ID-on-execution bit when all execute + bits are currently clear and none are being set + are ignored. + + Requests to clear all execute bits also clear the + set-user-ID-on-execution and set-group-ID-on-exe- + cution bits. + + Requests to clear the set-user-ID-on-execution or + set-group-ID-on-execution bits when all execute + bits are currently clear are ignored. However, if + the command ls -l file writes an s in the posi- + tion indicating that the set-user-ID-on-execution + or set-group-ID-on-execution is set, the commands + chmod u-s file or chmod g-s file, respectively, + shall not be ignored. + + When using the symbolic mode form on other file types, + it is implementation-defined whether or not requests to + set or clear the set-user-ID-on-execution or set-group- + ID-on-execution bits are honored. + + If the who symbol o is used in conjunction with the perm + symbol s with no other who symbols being specified, the + set-user-ID-on-execution and set-group-ID-on-execution + bits shall not be modified. It shall not be an error to + specify the who symbol o in conjunction with the perm + symbol s. + + The perm symbol t shall specify the S_ISVTX bit. When + used with a file of type directory, it can be used with + the who symbol a, or with no who symbol. It shall not be + an error to specify a who symbol of u, g, or o in con- + junction with the perm symbol t, but the meaning of + these combinations is unspecified. The effect when + using the perm symbol t with any file type other than + directory is unspecified. + + For an octal integer mode operand, the file mode bits + shall be set absolutely. + + For each bit set in the octal number, the corresponding + file permission bit shown in the following table shall + be set; all other file permission bits shall be cleared. + For regular files, for each bit set in the octal number + corresponding to the set-user-ID-on-execution or the + set-group-ID-on-execution, bits shown in the following + table shall be set; if these bits are not set in the + octal number, they are cleared. For other file types, it + is implementation-defined whether or not requests to set + or clear the set-user-ID-on-execution or set-group-ID- + on-execution bits are honored. +Octal Mode Bit Octal Mode Bit Octal Mode Bit Octal Mode Bit +4000 S_ISUID 0400 S_IRUSR 0040 S_IRGRP 0004 S_IROTH +2000 S_ISGID 0200 S_IWUSR 0020 S_IWGRP 0002 S_IWOTH +1000 S_ISVTX 0100 S_IXUSR 0010 S_IXGRP 0001 S_IXOTH + + When bits are set in the octal number other than those + listed in the table above, the behavior is unspecified. + + Grammar for chmod + The grammar and lexical conventions in this section + describe the syntax for the symbolic_mode operand. The + general conventions for this style of grammar are + described in Grammar Conventions . A valid symbolic_mode + can be represented as the non-terminal symbol sym- + bolic_mode in the grammar. This formal syntax shall take + precedence over the preceding text syntax description. + + The lexical processing is based entirely on single char- + acters. Implementations need not allow <blank>s within + the single argument being processed. + + + %start symbolic_mode + %% + + + symbolic_mode : clause + | symbolic_mode ',' clause + ; + + + clause : actionlist + | wholist actionlist + ; + + + wholist : who + | wholist who + ; + + + who : 'u' | 'g' | 'o' | 'a' + ; + + + actionlist : action + | actionlist action + ; + + + action : op + | op permlist + | op permcopy + ; + + + permcopy : 'u' | 'g' | 'o' + ; + + + op : '+' | '-' | '=' + ; + + + permlist : perm + | perm permlist + ; + + + + perm : 'r' | 'w' | 'x' | 'X' | 's' | 't' + ; + +EXIT STATUS + The following exit values shall be returned: + + 0 The utility executed successfully and all + requested changes were made. + + >0 An error occurred. + + +CONSEQUENCES OF ERRORS + Default. + + The following sections are informative. + +APPLICATION USAGE + Some implementations of the chmod utility change the + mode of a directory before the files in the directory + when performing a recursive ( -R option) change; others + change the directory mode after the files in the direc- + tory. If an application tries to remove read or search + permission for a file hierarchy, the removal attempt + fails if the directory is changed first; on the other + hand, trying to re-enable permissions to a restricted + hierarchy fails if directories are changed last. Users + should not try to make a hierarchy inaccessible to them- + selves. + + Some implementations of chmod never used the process' + umask when changing modes; systems conformant with this + volume of IEEE Std 1003.1-2001 do so when who is not + specified. Note the difference between: + + + chmod a-w file + + which removes all write permissions, and: + + + chmod -- -w file + + which removes write permissions that would be allowed if + file was created with the same umask. + + Conforming applications should never assume that they + know how the set-user-ID and set-group-ID bits on direc- + tories are interpreted. + +EXAMPLES +Mode Results +a+= Equivalent to a+, a=; clears all file mode bits. +go+-w Equivalent to go+, go- w; clears group and other write bits. +g=o-w Equivalent to g= o, g- w; sets group bit to match other bits and then clears group write bit. +g-r+w Equivalent to g- r, g+ w; clears group read bit and sets group write bit. +uo=g Sets owner bits to match group bits and sets other bits to match group bits. + +RATIONALE + The functionality of chmod is described substantially + through references to concepts defined in the System + Interfaces volume of IEEE Std 1003.1-2001. In this way, + there is less duplication of effort required for + describing the interactions of permissions. However, the + behavior of this utility is not described in terms of + the chmod() function from the System Interfaces volume + of IEEE Std 1003.1-2001 because that specification + requires certain side effects upon alternate file access + control mechanisms that might not be appropriate, + depending on the implementation. + + Implementations that support mandatory file and record + locking as specified by the 1984 /usr/group standard + historically used the combination of set-group-ID bit + set and group execute bit clear to indicate mandatory + locking. This condition is usually set or cleared with + the symbolic mode perm symbol l instead of the perm sym- + bols s and x so that the mandatory locking mode is not + changed without explicit indication that that was what + the user intended. Therefore, the details on how the + implementation treats these conditions must be defined + in the documentation. This volume of + IEEE Std 1003.1-2001 does not require mandatory locking + (nor does the System Interfaces volume of + IEEE Std 1003.1-2001), but does allow it as an exten- + sion. However, this volume of IEEE Std 1003.1-2001 does + require that the ls and chmod utilities work consis- + tently in this area. If ls -l file indicates that the + set-group-ID bit is set, chmod g-s file must clear it + (assuming appropriate privileges exist to change modes). + + The System V and BSD versions use different exit status + codes. Some implementations used the exit status as a + count of the number of errors that occurred; this prac- + tice is unworkable since it can overflow the range of + valid exit status values. This problem is avoided here + by specifying only 0 and >0 as exit values. + + The System Interfaces volume of IEEE Std 1003.1-2001 + indicates that implementation-defined restrictions may + cause the S_ISUID and S_ISGID bits to be ignored. This + volume of IEEE Std 1003.1-2001 allows the chmod utility + to choose to modify these bits before calling chmod() + (or some function providing equivalent capabilities) for + non-regular files. Among other things, this allows + implementations that use the set-user-ID and set-group- + ID bits on directories to enable extended features to + handle these extensions in an intelligent manner. + + The X perm symbol was adopted from BSD-based systems + because it provides commonly desired functionality when + doing recursive ( -R option) modifications. Similar + functionality is not provided by the find utility. His- + torical BSD versions of chmod, however, only supported X + with op+; it has been extended in this volume of + IEEE Std 1003.1-2001 because it is also useful with op=. + (It has also been added for op- even though it dupli- + cates x, in this case, because it is intuitive and eas- + ier to explain.) + + The grammar was extended with the permcopy non-terminal + to allow historical-practice forms of symbolic modes + like o= u -g (that is, set the "other" permissions to + the permissions of "owner" minus the permissions of + "group"). + +FUTURE DIRECTIONS + None. + +SEE ALSO + ls , umask , the System Interfaces volume of + IEEE Std 1003.1-2001, chmod() + +COPYRIGHT + Portions of this text are reprinted and reproduced in + electronic form from IEEE Std 1003.1, 2003 Edition, + Standard for Information Technology -- Portable Operat- + ing System Interface (POSIX), The Open Group Base Speci- + fications Issue 6, Copyright (C) 2001-2003 by the Insti- + tute of Electrical and Electronics Engineers, Inc and + The Open Group. In the event of any discrepancy between + this version and the original IEEE and The Open Group + Standard, the original IEEE and The Open Group Standard + is the referee document. The original Standard can be + obtained online at http://www.open- + group.org/unix/online.html . + + + +POSIX 2003 chmod(P) |