access - Determines the accessibility of a file
#include <unistd.h>
int access(
const char *path,
int access_mode );
Interfaces documented on this reference page conform to
industry standards as follows:
access(): XSH4.0, XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Points to the file pathname. When the path parameter
refers to a symbolic link, the access() function returns
information about the file pointed to by the symbolic
link.
Permission to access all components of the path
parameter is determined by using a real user ID
instead of an effective user ID, and a group access
list (including a real group ID) instead of an
effective group ID. Specifies the type of access.
The bit pattern contained in the access_mode parameter
is constructed by a logical OR of the following
values: Checks read permission. Checks write
permission. Checks execute (search) permission.
Checks to see if the file exists.
The access() function checks for accessibility of the file
specified by a pathname.
Only access bits are checked. A directory may be indicated
as writable by access(), but an attempt to open it for
writing will fail (although files may be created there); a
file's access bits may indicate that it is executable, but
the execve() function can fail if the file does not contain
the proper format.
The access() function is supported for multi-threaded
applications.
Upon successful completion, the access() function returns
value of 0 (zero). Otherwise, a value of -1 is returned
and errno is set to indicate the error.
If the access() function fails, access to the file specified
by the path parameter is denied and errno may be set
to one of the following values: Permission bits of the
file mode do not permit the requested access, or search
permission is denied on a component of the path prefix.
The owner of a file has permission checked with respect to
the ``user'' read, write, and execute mode bits, members
of the file's group other than the owner have permission
checked with respect to the ``group'' mode bits, and all
others have permissions checked with respect to the
``other'' mode bits. The path parameter points outside
the allocated address space of the process. [Tru64
UNIX] The pathname contains a character with the highorder
bit set. [Tru64 UNIX] An I/O error occurred while
reading from or writing to the file system. Too many symbolic
links were encountered in translating the pathname.
A component of a pathname exceeded PATH_MAX characters, or
an entire pathname exceeded NAME_MAX characters. The
named file does not exist or is an empty string. A component
of the path prefix is not a directory. Write access
is requested for a file on a read-only file system.
Functions: chmod(2), stat(2) eaccess(3)
Standards: standards(5)
access(2)
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