dup - duplicate an open file descriptor #include <u.h>

#include <libc.h>

int dup(int oldfd, int newfd)

Given a file descriptor, oldfd , referring to an open file, dup returns a new file descriptor referring to the same file. If newfd is in the range of legal file descriptors dup will use that for the new file descriptor (closing any old file associated with newfd); if newfd is -1 the system chooses the lowest available file descriptor. /sys/src/libc/9syscall intro (2), dup (3) Sets errstr .