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Linux 2.6 - man page for stdio (linux section 3)

STDIO(3)			    Linux Programmer's Manual				 STDIO(3)

NAME
       stdio - standard input/output library functions

SYNOPSIS
       #include <stdio.h>

       FILE *stdin;
       FILE *stdout;
       FILE *stderr;

DESCRIPTION
       The  standard  I/O  library provides a simple and efficient buffered stream I/O interface.
       Input and output is mapped into logical data streams and the physical I/O  characteristics
       are  concealed.	 The functions and macros are listed below; more information is available
       from the individual man pages.

       A stream is associated with an external file (which may be a physical device) by opening a
       file,  which may involve creating a new file.  Creating an existing file causes its former
       contents to be discarded.  If a file can support positioning  requests  (such  as  a  disk
       file,  as opposed to a terminal) then a file position indicator associated with the stream
       is positioned at the start of the file (byte zero), unless the file is opened with  append
       mode.   If  append  mode is used, it is unspecified whether the position indicator will be
       placed at the start or the end of the file.  The position indicator is maintained by  sub-
       sequent	reads,	writes	and  positioning requests.  All input occurs as if the characters
       were read by successive calls to the fgetc(3) function; all output takes place as  if  all
       characters were written by successive calls to the fputc(3) function.

       A  file	is  disassociated  from a stream by closing the file.  Output streams are flushed
       (any unwritten buffer contents are transferred to the host environment) before the  stream
       is  disassociated from the file.  The value of a pointer to a FILE object is indeterminate
       after a file is closed (garbage).

       A file may be subsequently reopened, by the same or another  program  execution,  and  its
       contents  reclaimed  or	modified  (if  it can be repositioned at the start).  If the main
       function returns to its original caller, or the exit(3) function is called, all open files
       are closed (hence all output streams are flushed) before program termination.  Other meth-
       ods of program termination, such as abort(3) do not bother about closing files properly.

       At program startup, three text streams are predefined and need not be  opened  explicitly:
       standard input (for reading conventional input), standard output (for writing conventional
       input), and standard error (for writing diagnostic output).  These streams are abbreviated
       stdin,stdout  and  stderr.   When opened, the standard error stream is not fully buffered;
       the standard input and output streams are fully buffered if and only if the streams do not
       refer to an interactive device.

       Output streams that refer to terminal devices are always line buffered by default; pending
       output to such streams is written automatically whenever an input stream that refers to	a
       terminal  device  is  read.   In  cases	where a large amount of computation is done after
       printing part of a line on an output terminal, it is necessary to fflush(3)  the  standard
       output before going off and computing so that the output will appear.

       The  stdio  library is a part of the library libc and routines are automatically loaded as
       needed by the compilers cc(1) and pc(1).  The SYNOPSIS sections of  the	following  manual
       pages  indicate	which include files are to be used, what the compiler declaration for the
       function looks like and which external variables are of interest.

       The following are defined as macros; these names may not be reused without first  removing
       their  current  definitions  with #undef: BUFSIZ, EOF, FILENAME_MAX, FOPEN_MAX, L_cuserid,
       L_ctermid, L_tmpnam, NULL, SEEK_END, SEEK_SET, SEEK_CUR, TMP_MAX, clearerr, feof,  ferror,
       fileno,	getc,  getchar,  putc,	putchar, stderr, stdin, stdout.  Function versions of the
       macro functions feof, ferror, clearerr, fileno, getc, getchar, putc, and putchar exist and
       will be used if the macros definitions are explicitly removed.

   List of functions
       Function      Description
       -------------------------------------------------------------------
       clearerr      check and reset stream status
       fclose	     close a stream
       fdopen	     stream open functions
       feof	     check and reset stream status
       ferror	     check and reset stream status
       fflush	     flush a stream
       fgetc	     get next character or word from input stream
       fgetpos	     reposition a stream
       fgets	     get a line from a stream
       fileno	     return the integer descriptor of the argument stream
       fopen	     stream open functions
       fprintf	     formatted output conversion
       fpurge	     flush a stream
       fputc	     output a character or word to a stream
       fputs	     output a line to a stream
       fread	     binary stream input/output
       freopen	     stream open functions
       fscanf	     input format conversion
       fseek	     reposition a stream
       fsetpos	     reposition a stream
       ftell	     reposition a stream
       fwrite	     binary stream input/output
       getc	     get next character or word from input stream
       getchar	     get next character or word from input stream
       gets	     get a line from a stream
       getw	     get next character or word from input stream
       mktemp	     make temporary filename (unique)
       perror	     system error messages
       printf	     formatted output conversion
       putc	     output a character or word to a stream
       putchar	     output a character or word to a stream
       puts	     output a line to a stream
       putw	     output a character or word to a stream
       remove	     remove directory entry
       rewind	     reposition a stream
       scanf	     input format conversion
       setbuf	     stream buffering operations
       setbuffer     stream buffering operations
       setlinebuf    stream buffering operations
       setvbuf	     stream buffering operations
       sprintf	     formatted output conversion
       sscanf	     input format conversion
       strerror      system error messages
       sys_errlist   system error messages
       sys_nerr      system error messages
       tempnam	     temporary file routines
       tmpfile	     temporary file routines
       tmpnam	     temporary file routines
       ungetc	     un-get character from input stream
       vfprintf      formatted output conversion
       vfscanf	     input format conversion
       vprintf	     formatted output conversion
       vscanf	     input format conversion
       vsprintf      formatted output conversion
       vsscanf	     input format conversion

CONFORMING TO
       The stdio library conforms to C89.

SEE ALSO
       close(2), open(2), read(2), write(2), stdout(3), unlocked_stdio(3)

COLOPHON
       This  page  is  part of release 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at
       http://www.kernel.org/doc/man-pages/.

					    2001-12-26					 STDIO(3)


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