access(2)                                               access(2)



NAME
     access - determine accessibility of a file

SYNOPSIS
     #include<unistd.h>
     int access(path,amode)
     char *path;
     int amode;

DESCRIPTION
     access is used to determine the accessibility of a file.
     The path points to a pathname naming a file.  access checks
     the named file for accessibility according to the bit
     pattern contained in amode, by using the real user ID in
     place of the effective user ID and the real group ID in
     place of the effective group ID.  The bit pattern contained
     in amode is constructed as follows:

          04   read
          02   write
          01   execute (search)
          00   check existence of file

     For the POSIX environment, the following values are defined
     for passing amode as the value of <unistd.h>:

          R_OK 04   read
          W_OK 02   write
          X_OK 01   executable file or searchable directory
          F_OK 00   check existence of file

STATUS MESSAGES AND VALUES
     If the requested access is permitted, a value of 0 is
     returned.  Otherwise, a value of -1 is returned and errno is
     set to indicate the error.

     The access command will fail if one or more of the following
     is true:

     ENAMETOOLONG
          A component of a pathname exceeded NAME_MAX characters,
          or an entire pathname exceeded PATH_MAX.

     ELOOP
          Too many symbolic links were encountered in translating
          a pathname.

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

     ENOENT
          Read, write, or execute (search) permission is



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access(2)                                               access(2)



          requested for a null pathname.

     ENOENT
          The named file does not exist.

     EACCES
          Search permission is denied on a component of the path
          prefix.

     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 that is being executed.

             Note:  If you are running network file system
             (NFS) and you are accessing a shared binary
             remotely, it is possible that you will not get
             this errno.


     EACCESS
          Permission bits of the file mode do not permit the
          requested access.

     EFAULT
          The path points outside the allocated address space for
          the process.

     EINVAL
          Value of amode is invalid.

     The owner of a file has permission checked with respect to
     the ``owner'' read, write, and execute mode bits.  Members
     of the file's group, other than the owner, have permissions
     checked with respect to the ``group'' mode bits, and all
     others have permissions checked with respect to the
     ``other'' mode bits.

     The superuser is always granted execute permission even
     though execute permission is meaningful only for directories
     and regular files and even though exec requires that at
     least one execute mode bit is set for the regular file to be
     executable.

     Notice that only access bits are checked.  A directory may
     be announced as writable by access, but an attempt to open
     it for writing will fail because writing into the directory
     structure itself is not allowed, even though files may be
     created there.  A file may look executable, but exec will



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access(2)                                               access(2)



     fail unless it is in the proper format.

SEE ALSO
     chmod(2), stat(2)



















































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