dup() COHERENT System Call dup() Duplicate a file descriptor int dup(fd) int fd; dup duplicates the existing file descriptor fd, and returns the new descriptor. The returned value is the smallest file descrip- tor that is not already in use by the calling process. ***** See Also ***** COHERENT system calls, dup2(), fopen(), fdopen(), STDIO ***** Diagnostics ***** dup returns a number less than zero when an error occurs, such as a bad file descriptor or no file descriptor available. COHERENT Lexicon Page 1