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access (2)
  • access (1) ( Solaris man: Команды и прикладные программы пользовательского уровня )
  • access (1) ( Linux man: Команды и прикладные программы пользовательского уровня )
  • access (2) ( Solaris man: Системные вызовы )
  • >> access (2) ( FreeBSD man: Системные вызовы )
  • access (2) ( Русские man: Системные вызовы )
  • access (2) ( Linux man: Системные вызовы )
  • access (3) ( Solaris man: Библиотечные вызовы )
  • access (3) ( POSIX man: Библиотечные вызовы )
  • access (5) ( Русские man: Форматы файлов )
  • access (5) ( Linux man: Форматы файлов )
  • Ключ access обнаружен в базе ключевых слов.

  • BSD mandoc
     

    NAME

    
    
    access , eaccess
    
     - check accessibility of a file
    
     
    

    LIBRARY

    Lb libc
    
     
    

    SYNOPSIS

       #include <unistd.h>
    int access (const char *path int mode);
    int eaccess (const char *path int mode);
     

    DESCRIPTION

    The access ();
    and eaccess ();
    system calls check the accessibility of the file named by the Fa path argument for the access permissions indicated by the Fa mode argument. The value of Fa 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 Sx File Access Permission section of intro(2).

    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

    Rv -std  

    ERRORS

    Access to the file is denied if:

    Bq Er ENOTDIR
    A component of the path prefix is not a directory.
    Bq Er ENAMETOOLONG
    A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
    Bq Er ENOENT
    The named file does not exist.
    Bq Er ELOOP
    Too many symbolic links were encountered in translating the pathname.
    Bq Er EROFS
    Write access is requested for a file on a read-only file system.
    Bq Er ETXTBSY
    Write access is requested for a pure procedure (shared text) file presently being executed.
    Bq Er 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.
    Bq Er EFAULT
    The Fa path argument points outside the process's allocated address space.
    Bq Er EIO
    An I/O error occurred while reading from or writing to the file system.

     

    SECURITY CONSIDERATIONS

    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.

    access ();
    remains useful for providing clues to users as to whether operations make sense for particular filesystem objects (e.g. 'delete' menu item only highlighted in a writable folder ... avoiding interpretation of the st_mode bits that the application might not understand -- e.g. in the case of AFS). It also allows a cheaper file existence test than stat(2).  

    SEE ALSO

    chmod(2), intro(2), stat(2)  

    STANDARDS

    The access ();
    system call is expected to conform to St -p1003.1-90 .  

    HISTORY

    The access ();
    function appeared in AT&T System v7 .


     

    Index

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


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