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FTOK(3) BSD Library Functions Manual FTOK(3)
ftok -- create IPC identifier from path name
Standard C Library (libc, -lc)
ftok(const char *path, int id);
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
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
The ftok() function will return -1 if path does not exist or if it cannot be accessed by the
msgget(2), semget(2), shmget(2)
The ftok() function originates with System V and is typically used by programs that use the
System V IPC routines.
Thorsten Lockert <email@example.com>
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.
BSD July 9, 2009 BSD
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