<TITLE>freopen</TITLE> <body bgcolor="#ffffcc"> <hr> <pre> <h3>FOPEN(3) Linux Programmer's Manual FOPEN(3) </h3> <h3>NAME </h3> fopen, fdopen, freopen - stream open functions <h3>SYNOPSIS </h3> #include <stdio.h> FILE *fopen( char *path, char *mode); FILE *fdopen( int fildes, char *mode); FILE *freopen( char *path, char *mode, FILE *stream); <h3>DESCRIPTION </h3> The fopen function opens the file whose name is the string pointed to by path and associates a stream with it. The argument mode points to a string beginning with one of the following sequences (Additional characters may follow these sequences.): r Open text file for reading. The stream is posi- tioned at the beginning of the file. r+ Open for reading and writing. The stream is posi- tioned at the beginning of the file. w Truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file. w+ 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. a Open for writing. The file is created if it does not exist. The stream is positioned at the end of the file. a+ Open for reading and writing. The file is created if it does not exist. The stream is positioned at the end of the file. The mode string can also include the letter ``b'' either as a third character or as a character between the charac- ters in any of the two-character strings described above. This is strictly for compatibility with ANSI C3.159-1989 (``ANSI C'') and has no effect; the ``b'' is ignored. Linux may not behave this way. Any created files will have mode S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH (0666), as modified by the process' umask value (see umask(2). Reads and writes may be intermixed on read/write streams in any order, and do not require an intermediate seek as <h3>BSD MANPAGE 29 November 1993 1 </h3> <h3>FOPEN(3) Linux Programmer's Manual FOPEN(3) </h3> in previous versions of stdio. This is not portable to other systems, however, and may not work under Linux (someone should find out and fix this manpage); ANSI C requires that a file positioning function intervene between output and input, unless an input operation encounters end-of-file. The fdopen function associates a stream with the existing file descriptor, fildes. The mode of the stream must be compatible with the mode of the file descriptor. The freopen function opens the file whose name is the string pointed to by path and associates the stream pointed to by stream with it. The original stream (if it exists) is closed. The mode argument is used just as in the fopen function. The primary use of the freopen func- tion is to change the file associated with a standard text stream (stderr, stdin, or stdout). <h3>RETURN VALUES </h3> Upon successful completion fopen, fdopen and freopen return a FILE pointer. Otherwise, NULL is returned and the global variable errno is set to indicate the error. <h3>ERRORS </h3> EINVAL The mode provided to fopen, fdopen, or freopen was invalid. The fopen, fdopen and freopen functions may also fail and set errno for any of the errors specified for the routine malloc(3). The fopen function may also fail and set errno for any of the errors specified for the routine open(2). The fdopen function may also fail and set errno for any of the errors specified for the routine fcntl(2). The freopen function may also fail and set errno for any of the errors specified for the routines open(2), fclose(3) and fflush(3). </pre> <hr> <h3>SEE ALSO </h3><p> <a href=open.htm>open</a>, <a href=fclose.htm>fclose</a>, <pre> <h3>STANDARDS </h3> The fopen and freopen functions conform to ANSI C3.159-1989 (``ANSI C''). The fdopen function conforms to IEEE Std1003.1-1988 (``POSIX''). <h3>BSD MANPAGE 29 November 1993 2 </h3> </pre> <P> <hr> <p> <center> <table border=2 width=80%> <tr align=center> <td width=25%> <a href=../index.htm>Top</a> </td><td width=25%> <a href=../master_index.html>Master Index</a> </td><td width=25%> <a href=../SYNTAX/keywords.html>Keywords</a> </td><td width=25%> <a href=../FUNCTIONS/index.htm>Functions</a> </td> </tr> </table> </center> <p> <hr> This manual page was brought to you by <i>mjl_man V-2.0</i>
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