Identification of controlling terminal.
Syntax | 
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   #include <stdio.h>
   char *ctermid(char *s);
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Parameters | 
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- s
 
The address of an array that will receive the pathname fo the current controlling terminal.
Return Values | 
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If s is not NULL then it points to an array of char L_ctermid bytes long, or longer, as defined in <stdio.h>.
An empty string is returned if the ctermid() function is unsuccessful.
Description | 
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The ctermid() function returns a string that can be used as a filename for referencing a terminal.
If a pathname is returned, access is not guaranteed.
Implementation Considerations | 
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None.
Errors | 
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None.
See Also | 
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ttyname(), POSIX.1 (Section 4.7.2)