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FTOK(3)			    Library Functions Manual		       FTOK(3)

NAME
       ftok -- create IPC identifier from path name

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<sys/ipc.h>

       key_t
       ftok(const char *path, int id);

DESCRIPTION
       The  ftok()  function  attempts to create a unique key suitable for use
       with the	msgget(2), semget(2) and shmget(2) functions given the path of
       an existing file	and a user-selectable id.

       The specified path must specify an existing file	that is	accessible  to
       the  calling  process  or the call will fail.  Also, note that links to
       files will return the same key, given the same id.

RETURN VALUES
       The ftok() function will	return -1 if path does not exist or if it can-
       not be accessed by the calling process.

SEE ALSO
       msgget(2), semget(2), shmget(2)

HISTORY
       The ftok() function originates with System V and	is typically  used  by
       programs	that use the System V IPC routines.

AUTHORS
       Thorsten	Lockert	<tholo@sigmasoft.com>

BUGS
       The returned key	is computed based on the device	minor number and inode
       of the specified	path in	combination with the lower 8 bits of the given
       id.   Thus  it  is  quite  possible for the routine to return duplicate
       keys.

FreeBSD	14.3		       November	28, 2022		       FTOK(3)

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