[1] Unix manual page for dup2

Unix Manual Page for dup2

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NAME

     dup2 - duplicate an open file descriptor

SYNOPSIS

      #include <unistd.h>

     int dup2(int fildes, int fildes2);

 

DESCRIPTION

The dup2() function causes the file  descriptor  fildes2  to
     refer  to  the same file as fildes. The fildes argument is a
     file descriptor referring to an open file, and fildes2 is  a
     non-negative  integer  less  than  the current value for the
     maximum number of open file descriptors  allowed the calling
     process.   See getrlimit(2). If fildes2 already refers to an
     open file, not fildes, it is closed first. If fildes2 refers
     to fildes, or if fildes is not a valid open file descriptor,
     fildes2 will not be closed first.

     The  dup2()  function  is   equivalent   to    fcntl(fildes,
     F_DUP2FD, fildes2).

 

RETURN VALUES

Upon successful completion a non-negative integer represent-
     ing  the  file  descriptor  is  returned.  Otherwise,  -1 is
     returned and errno is set to indicate the error.

 

ERRORS

The dup2() function will fail if:

     EBADF The fildes argument is not a valid open file  descrip-
           tor.

     EBADF The files2 argument is negative or is  not  less  than
           the     current    resource    limit    returned    by
           getrlimit(RLIMIT_NOFILE, ...).

     EINTR A signal was caught during the dup2() call.

     EMFILE
           The process has too many open files.  See  fcntl(2).

 

ATTRIBUTES

1. See attributes(5) for descriptions of the  following  attri-
        butes:
   
        ____________________________________________________________
       |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
       |_____________________________|_____________________________|
       | MT-Level                    | Safe                        |
       |_____________________________|_____________________________|

 

SEE ALSO

 close(2),   creat(2),   exec(2),   fcntl(2),   getrlimit(2),
     open(2), pipe(2), lockf(3C), attributes(5)

 

 

원문

http://www.scit.wlv.ac.uk/cgi-bin/mansec?3C+dup2

 

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