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NAME    [Toc]    [Back]

     access, eaccess -- check accessibility of a file

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     access(const char *path, int mode);

     eaccess(const char *path, int mode);

DESCRIPTION    [Toc]    [Back]

     The access() and eaccess() system calls check the accessibility of the
     file named by the path argument for the access permissions indicated by
     the mode argument.  The value of mode is either the bitwise-inclusive OR
     of the access permissions to be checked (R_OK for read permission, W_OK
     for write permission, and X_OK for execute/search permission), or the
     existence test (F_OK).

     For additional information, see the File Access Permission section of

     The eaccess() system call uses the effective user ID and the group access
     list to authorize the request; the access() system call uses the real
     user ID in place of the effective user ID, the real group ID in place of
     the effective group ID, and the rest of the group access list.

     Even if a process's real or effective user has appropriate privileges and
     indicates success for X_OK, the file may not actually have execute permission
 bits set.	Likewise for R_OK and W_OK.

RETURN VALUES    [Toc]    [Back]

     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the

ERRORS    [Toc]    [Back]

     Access to the file is denied if:

     [ENOTDIR]		A component of the path prefix is not a directory.

     [ENAMETOOLONG]	A component of a pathname exceeded 255 characters, or
			an entire path name exceeded 1023 characters.

     [ENOENT]		The named file does not exist.

     [ELOOP]		Too many symbolic links were encountered in translating
 the pathname.

     [EROFS]		Write access is requested for a file on a read-only
			file system.

     [ETXTBSY]		Write access is requested for a pure procedure (shared
			text) file presently being executed.

     [EACCES]		Permission bits of the file mode do not permit the
			requested access, or search permission is denied on a
			component of the path prefix.

     [EFAULT]		The path argument points outside the process's allocated
 address space.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system.


     The access() system call is a potential security hole due to race conditions
 and should never be used.  Set-user-ID and set-group-ID applications
 should restore the effective user or group ID, and perform actions
     directly rather than use access() to simulate access checks for the real
     user or group ID.	The eaccess() system call likewise may be subject to
     races if used inappropriately.

SEE ALSO    [Toc]    [Back]

     chmod(2), intro(2), stat(2)

STANDARDS    [Toc]    [Back]

     The access() system call is expected to conform to ISO/IEC 9945-1:1990

HISTORY    [Toc]    [Back]

     The access() function appeared in Version 7 AT&T UNIX.

FreeBSD 5.2.1		      September 21, 2001		 FreeBSD 5.2.1
[ Back ]
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