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ACCESS(2)		  FreeBSD System Calls Manual		     ACCESS(2)

NAME
     access, eaccess --	check accessibility of a file

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     access(const char *path, int mode);

     int
     eaccess(const char	*path, int mode);

DESCRIPTION
     The access() and eaccess()	functions 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 exis-
     tence test	(F_OK).

     For additional information, see the File Access Permission	section	of
     intro(2).

     The eaccess() call	uses the effective user	ID and the group access	list
     to	authorize the request; the access() call uses the real user ID in
     place of the effective user ID, the real group ID in place	of the effec-
     tive 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	per-
     mission bits set.	Likewise for R_OK and W_OK.

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

ERRORS
     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 translat-
			ing 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]		path points outside the	process's allocated address
			space.

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

SECURITY CONSIDERATIONS
     The access() 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() call likewise may	be subject to races if used
     inappropriately.

SEE ALSO
     chmod(2), intro(2), stat(2)

STANDARDS
     The access() function call	is expected to conform to ISO/IEC 9945-1:1990
     (``POSIX.1'').

HISTORY
     An	access() function call appeared	in Version 7 AT&T UNIX.

FreeBSD	9.3		      September	21, 2001		   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SECURITY CONSIDERATIONS | SEE ALSO | STANDARDS | HISTORY

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