Returns a key used in calls to msgget(), semget(), and shmget() function calls.
Syntax |
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#include <sys/types.h>
#include <sys/ipc.h>
key_t ftok (char *pathname, char id);
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Parameters |
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- pathname
Passes a pointer to a string containing the pathname of a file accessible to the calling process.
- id
Passes a character used to further qualify the returned key.
Return Values |
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- ≠-1
Key value returned.
- -1
Error. The specified pathname does not exist or is not accessible to the calling process.
Description |
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The ftok() function can be used to return a key based on both pathname and id. This key can be used in subsequent calls to the SVID IPC msgget(), semget(), and shmget() functions.
A different key is returned when called with the same pathname but a different character is passed in id.
Implementation Considerations |
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None.
Errors |
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If an error occurs, errno is set to the following value.
| EINVAL | CAUSE | The pathname parameter points to an invalid address, or pathname specifies a nonexistent file, or the caller does not have the correct access to the pathname. |
| | ACTION | Make sure that pathname points to a valid and existing pathname to which the caller has access. |
See Also |
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msgget(), semget(), shmget()
