.\" Copyright (c) 1990, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" This code is derived from software contributed to Berkeley by .\" Chris Torek and the American National Standards Committee X3, .\" on Information Processing Systems. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)fopen.3 8.1 (Berkeley) 6/4/93 .\" .TH FOPEN 3 "29 April 1997" GNO "Library Routines" .SH NAME .BR fopen , .BR fdopen , .BR freopen \- stream open functions .SH SYNOPSIS #include .sp 1 FILE *\fBfopen\fR(const char *\fIpath\fR, const char *\fImode\fR); .sp 1 FILE *\fBfdopen\fR(int \fIfildes\fR, const char *\fImode\fR); .sp 1 FILE *\fBfreopen\fR(const char *\fIpath\fR, const char *\fImode\fR, FILE *\fIstream\fR); .SH DESCRIPTION The .BR fopen function opens the file whose name is the string pointed to by .I path and associates a stream with it. .LP The argument .I mode points to a string beginning with one of the following sequences (Additional characters may follow these sequences.): .RS .IP \fBr\fR Open text file for reading. The stream is positioned at the beginning of the file. .IP \fBr+\fR Open for reading and writing. The stream is positioned at the beginning of the file. .IP \fBw\fR Truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file. .IP \fBw+\fR Open for reading and writing. The file is created if it does not exist, otherwise it is truncated. The stream is positioned at the beginning of the file. .IP \fBa\fR Open for writing. The file is created if it does not exist. The stream is positioned at the end of the file. .IP \fBa+\fR Open for reading and writing. The file is created if it does not exist. The stream is positioned at the end of the file. .RE .LP The .I mode string can also include the letter ``b'' either as a third character or as a character between the characters in any of the two-character strings described above. If the ``b'' is .I not specified, then the file is assumed to contain text. On input, carrige returns (``\\r'') will be translated into line feeds (``\\n''). The reverse translation will occur on output. If the ``b'' .I is specified, no such translation will occur. .LP Any created files will have mode .BR S_IRUSR \&| .BR S_IWUSR \&| .BR S_IRGRP \&| .BR S_IWGRP \&| .BR S_IROTH \&| .BR S_IWOTH " (0666)," as modified by the process' umask value (see .BR umask (2)). .LP The .BR fdopen function associates a stream with the existing file descriptor, .IR fildes The .I mode of the stream must be compatible with the mode of the file descriptor. See the section on BUGS. .LP The .BR freopen function opens the file whose name is the string pointed to by .I path and associates the stream pointed to by .I stream with it. The original stream (if it exists) is closed. The .I mode argument is used just as in the .BR fopen function. The primary use of the .BR freopen function is to change the file associated with a standard text stream .IR ( stderr , .IR stdin , or .IR stdout ). .SH RETURN VALUES Upon successful completion .BR fopen , .BR fdopen and .BR freopen return a FILE pointer. Otherwise, .BR NULL is returned and the global variable .IR errno is set to indicate the error. .SH ERRORS .RS .IP \fBEINVAL\fR The .I mode provided to .BR fopen , .BR fdopen , or .BR freopen was invalid. .RE .LP The .BR fopen , .BR fdopen and .BR freopen functions may also fail and set .IR errno for any of the errors specified for the routine .BR malloc (3). .LP The .BR fopen function may also fail and set .IR errno for any of the errors specified for the routine .BR open (2). .LP The .BR fdopen function may also fail and set .IR errno for any of the errors specified for the routine .BR fcntl (2) or .BR stat (2). .LP The .BR freopen function may also fail and set .IR errno for any of the errors specified for the routines .BR open (2), .BR fclose (3) and .BR fflush (3). .SH BUGS If .BR fdopen is passed a file descriptor in use by another stdio stream (such as that available from the .BR fileno macro), the result is currently undefined. If you need to do such an operation, you should .BR dup (2) the result of the .BR fileno macro before passing it to .BR fdopen . .LP Access bits are not currently checked for any file descriptor passed to .BR fdopen which is a character-special file. .SH SEE ALSO .BR open (2), .BR stat (2), .BR fclose (3), .BR fseek (3), .BR funopen (3) .SH STANDARDS The .BR fopen and .BR freopen functions conform to ANSI/C. The .BR fdopen function conforms to POSIX 1003.1 (1988).