Linux / Unix Command: ftok

Command Library

NAME

ftok - convert a pathname and a project identifier to a System V IPC key  

SYNOPSIS

# include <sys/types.h>
# include <sys/ipc.h>

key_t ftok(const char *pathname, int proj_id);  

DESCRIPTION

The ftok function uses the identity of the file named by the given pathname (which must refer to an existing, accessible file) and the least significant 8 bits of proj_id (which must be nonzero) to generate a key_t type System V IPC key, suitable for use with msgget(2), semget(2), or shmget(2).

The resulting value is the same for all pathnames that name the same file, when the same value of proj_id is used. The value returned should be different when the (simultaneously existing) files or the project IDs differ.  

RETURN VALUE

On success the generated key_t value is returned. On failure -1 is returned, with errno indicating the error as for the stat(2) system call.  

CONFORMING TO

XPG4  

SEE ALSO

ipc(5), msgget(2), semget(2), shmget(2), stat(2)

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