dup.3 (695B)
1 .TH DUP 3 2 .SH NAME 3 dup \- duplicate an open file descriptor 4 .SH SYNOPSIS 5 .B #include <u.h> 6 .br 7 .B #include <libc.h> 8 .PP 9 .B 10 int dup(int oldfd, int newfd) 11 .SH DESCRIPTION 12 Given a file descriptor, 13 .IR oldfd , 14 referring to an open file, 15 .I dup 16 returns a new file descriptor referring to the same file. 17 .PP 18 If 19 .I newfd 20 is \-1 the system chooses the lowest available file descriptor. 21 Otherwise, 22 .I dup 23 will use 24 .I newfd 25 for the new file descriptor 26 (closing any old file associated with 27 .IR newfd ). 28 .SH SOURCE 29 .B \*9/src/lib9/dup.c 30 .SH DIAGNOSTICS 31 Sets 32 .IR errstr . 33 .SH BUGS 34 To avoid name conflicts with the underlying system, 35 .I dup 36 is a preprocessor macro defined as 37 .IR p9dup ; 38 see 39 .MR intro (3) .