strmode(3) [debian man page]
STRMODE(3) BSD Library Functions Manual STRMODE(3) NAME
strmode -- convert inode status information into a symbolic string LIBRARY
Utility functions from BSD systems (libbsd, -lbsd) SYNOPSIS
#include <bsd/string.h> void strmode(mode_t mode, char *bp); DESCRIPTION
The strmode() function converts a file mode (the type and permission information associated with an inode, see stat(2)) into a symbolic string which is stored in the location referenced by bp. This stored string is eleven characters in length plus a trailing NUL. The first character is the inode type, and will be one of the following: - regular file b block special c character special d directory l symbolic link p fifo s socket w whiteout ? unknown inode type The next nine characters encode three sets of permissions, in three characters each. The first three characters are the permissions for the owner of the file, the second three for the group the file belongs to, and the third for the ``other'', or default, set of users. Permission checking is done as specifically as possible. If read permission is denied to the owner of a file in the first set of permis- sions, the owner of the file will not be able to read the file. This is true even if the owner is in the file's group and the group permis- sions allow reading or the ``other'' permissions allow reading. If the first character of the three character set is an ``r'', the file is readable for that set of users; if a dash ``-'', it is not read- able. If the second character of the three character set is a ``w'', the file is writable for that set of users; if a dash ``-'', it is not writable. The third character is the first of the following characters that apply: S If the character is part of the owner permissions and the file is not executable or the directory is not searchable by the owner, and the set-user-id bit is set. S If the character is part of the group permissions and the file is not executable or the directory is not searchable by the group, and the set-group-id bit is set. T If the character is part of the other permissions and the file is not executable or the directory is not searchable by others, and the ``sticky'' (S_ISVTX) bit is set. s If the character is part of the owner permissions and the file is executable or the directory searchable by the owner, and the set- user-id bit is set. s If the character is part of the group permissions and the file is executable or the directory searchable by the group, and the set- group-id bit is set. t If the character is part of the other permissions and the file is executable or the directory searchable by others, and the ``sticky'' (S_ISVTX) bit is set. x The file is executable or the directory is searchable. - None of the above apply. The last character is a plus sign ``+'' if any there are any alternate or additional access control methods associated with the inode, other- wise it will be a space. SEE ALSO
chmod(1), find(1), stat(2), getmode(3), setmode(3) HISTORY
The strmode() function first appeared in 4.4BSD. BSD
July 28, 1994 BSD
Check Out this Related Man Page
CHMOD(1) BSD General Commands Manual CHMOD(1) NAME
chmod -- change file modes SYNOPSIS
chmod [-R [-H | -L | -P]] [-fh] mode file ... DESCRIPTION
The chmod utility modifies the file mode bits of the listed files as specified by the mode operand. The options are as follows: -H If the -R option is specified, symbolic links on the command line are followed. (Symbolic links encountered in the tree traversal are not followed.) -L If the -R option is specified, all symbolic links are followed. -P If the -R option is specified, no symbolic links are followed. -R Change the modes of the file hierarchies rooted in the files instead of just the files themselves. -f Do not display a diagnostic message or modify the exit status if chmod fails to change the mode of a file. -h If file is symbolic link, the mode of the link is changed. The -H, -L and -P options are ignored unless the -R option is specified. In addition, these options override each other and the command's actions are determined by the last one specified. Only the owner of a file or the super-user is permitted to change the mode of a file. EXIT STATUS
The chmod utility exits 0 on success, and >0 if an error occurs. MODES
Modes may be absolute or symbolic. An absolute mode is an octal number constructed by or'ing the following values: 4000 set-user-ID-on-execution 2000 set-group-ID-on-execution 1000 sticky bit, see chmod(2) 0400 read by owner 0200 write by owner 0100 execute (or search for directories) by owner 0070 read, write, execute/search by group 0007 read, write, execute/search by others The read, write, and execute/search values for group and others are encoded as described for owner. The symbolic mode is described by the following grammar: mode ::= clause [, clause ...] clause ::= [who ...] [action ...] last_action action ::= op [perm ...] last_action ::= op [perm ...] who ::= a | u | g | o op ::= + | - | = perm ::= r | s | t | w | x | X | u | g | o The who symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts of the mode bits, respectively. The who symbol ``a'' is equivalent to ``ugo''. The perm symbols represent the portions of the mode bits as follows: r The read bits. s The set-user-ID-on-execution and set-group-ID-on-execution bits. t The sticky bit. w The write bits. x The execute/search bits. X The execute/search bits if the file is a directory or any of the execute/search bits are set in the original (unmodified) mode. Operations with the perm symbol ``X'' are only meaningful in conjunction with the op symbol ``+'', and are ignored in all other cases. u The user permission bits in the mode of the original file. g The group permission bits in the mode of the original file. o The other permission bits in the mode of the original file. The op symbols represent the operation performed, as follows: + If no value is supplied for perm, the ``+'' operation has no effect. If no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is clear, is set. Otherwise, the mode bits represented by the specified who and perm values are set. - If no value is supplied for perm, the ``-'' operation has no effect. If no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is clear, is cleared. Otherwise, the mode bits represented by the specified who and perm values are cleared. = The mode bits specified by the who value are cleared, or, if no who value is specified, the owner, group and other mode bits are cleared. Then, if no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is clear, is set. Otherwise, the mode bits represented by the specified who and perm values are set. Each clause specifies one or more operations to be performed on the mode bits, and each operation is applied to the mode bits in the order specified. Operations upon the other permissions only (specified by the symbol ``o'' by itself), in combination with the perm symbols ``s'' or ``t'', are ignored. EXAMPLES
644 make a file readable by anyone and writable by the owner only. go-w deny write permission to group and others. =rw,+X set the read and write permissions to the usual defaults, but retain any execute permissions that are currently set. +X make a directory or file searchable/executable by everyone if it is already searchable/executable by anyone. 755 u=rwx,go=rx u=rwx,go=u-w make a file readable/executable by everyone and writable by the owner only. go= clear all mode bits for group and others. g=u-w set the group bits equal to the user bits, but clear the group write bit. SEE ALSO
chflags(1), install(1), chmod(2), stat(2), umask(2), fts(3), setmode(3), symlink(7), chown(8) STANDARDS
The chmod utility is expected to be IEEE Std 1003.2-1992 (``POSIX.2'') compatible with the exception of the perm symbol ``t'' which is not included in that standard. BUGS
There's no perm option for the naughty bits. BSD
January 22, 2010 BSD