freopen(3C)						   Standard C Library Functions 					       freopen(3C)

NAME

       freopen - open a stream

SYNOPSIS

       #include <stdio.h>

       FILE *freopen(const char *filename, const char *mode, FILE *stream);

DESCRIPTION

       The  freopen()  function first attempts to flush the stream and close any file descriptor associated with stream. Failure to flush or close
       the file successfully is ignored. The error and end-of-file indicators for the stream are cleared.

       The freopen() function opens the file whose pathname is the string pointed to by filename and associates the stream pointed  to	by  stream
       with it. The mode argument is used just as in fopen(3C).

       If  filename is a null pointer and the application comforms to SUSv3 (see standards(5)), the freopen() function attempts to change the mode
       of the stream to that specified by mode, as though the name of the file currently associated with the stream had been used.  The  following
       changes of mode are permitted, depending upon the access mode of the file descriptor underlying the stream:

	 o  When + is specified, the file descriptor mode must be O_RDWR.

	 o  When r is specified, the file descriptor mode must be O_RDONLY or O_RDWR.

	 o  When a or w is specified, the file descriptor mode must be O_WRONLY or O_RDWR.

       If the filename is a null pointer and the application does not comform to SUSv3, freopen() returns a null pointer.

       The original stream is closed regardless of whether the subsequent open succeeds.

       After  a successful call to the freopen() function, the orientation of the stream is cleared, the encoding rule is cleared, and the associ-
       ated mbstate_t object is set to describe an initial conversion state.

       The largest value that can be represented correctly in an object of type off_t will be established as the offset maximum in the	open  file
       description.

RETURN VALUES

       Upon  successful  completion, freopen() returns the value of stream. Otherwise, a null pointer is returned and errno is set to indicate the
       error.

ERRORS

       The freopen() function will fail if:

       EACCES	       Search permission is denied on a component of the path prefix, or the file exists and the permissions specified by mode are
		       denied, or the file does not exist and write permission is denied for the parent directory of the file to be created.

       EBADF	       The  application  comforms  to SUSv3, the filename argument is a null pointer, and either the underlying file descriptor is
		       not valid or the mode specified when the underlying file descriptor was opened does  not  support  the  file  access  modes
		       requested by the mode argument.

       EFAULT	       The application does not comform to SUSv3 and the filename argument is a null pointer.

       EINTR	       A signal was caught during freopen().

       EISDIR	       The named file is a directory and mode requires write access.

       ELOOP	       Too many symbolic links were encountered in resolving path.

       EMFILE	       There are {OPEN_MAX} file descriptors currently open in the calling process.

       ENAMETOOLONG    The length of the filename exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.

       ENFILE	       The maximum allowable number of files is currently open in the system.

       ENOENT	       A component of filename does not name an existing file or filename is an empty string.

       ENOSPC	       The  directory or file system that would contain the new file cannot be expanded, the file does not exist, and it was to be
		       created.

       ENOTDIR	       A component of the path prefix is not a directory.

       ENXIO	       The named file is a character special or block special file, and the device associated with  this  special  file  does  not
		       exist.

       EOVERFLOW       The current value of the file position cannot be represented correctly in an object of type off_t.

       EROFS	       The named file resides on a read-only file system and mode requires write access.

       The freopen() function may fail if:

       EINVAL	       The value of the mode argument is not valid.

       ENAMETOOLONG    Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.

       ENOMEM	       Insufficient storage space is available.

       ENXIO	       A request was made of a non-existent device, or the request was outside the capabilities of the device.

       ETXTBSY	       The file is a pure procedure (shared text) file that is being executed and mode requires write access.

USAGE

       The  freopen()  function  is  typically	used  to  attach the preopened streams associated with stdin, stdout and stderr to other files. By
       default stderr is unbuffered, but the use of freopen() will cause it to become buffered or line-buffered.

       The freopen() function has a transitional interface for 64-bit file offsets.  See lf64(5).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fclose(3C), fdopen(3C), fopen(3C), stdio(3C), attributes(5), lf64(5), standards(5)

SunOS 5.10							    24 Jul 2002 						       freopen(3C)