PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       setbuf — assign buffering to a stream

SYNOPSIS

       #include <stdio.h>

       void setbuf(FILE *restrict stream, char *restrict buf);

DESCRIPTION

       The functionality described on this reference page is aligned with the ISO C standard. Any
       conflict between the requirements described here and the ISO C standard is  unintentional.
       This volume of POSIX.1‐2017 defers to the ISO C standard.

       Except that it returns no value, the function call:

           setbuf(stream, buf)

       shall be equivalent to:

           setvbuf(stream, buf, _IOFBF, BUFSIZ)

       if buf is not a null pointer, or to:

           setvbuf(stream, buf, _IONBF, BUFSIZ)

       if buf is a null pointer.

RETURN VALUE

       The setbuf() function shall not return a value.

ERRORS

       Although the setvbuf() interface may set errno in defined ways, the value of errno after a
       call to setbuf() is unspecified.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       A common source of error is allocating buffer space as an ``automatic'' variable in a code
       block, and then failing to close the stream in the same block.

       With  setbuf(), allocating a buffer of BUFSIZ bytes does not necessarily imply that all of
       BUFSIZ bytes are used for the buffer area.

       Since errno is not required to be unchanged on success, in order to correctly  detect  and
       possibly recover from errors, applications should use setvbuf() instead of setbuf().

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.5, Standard I/O Streams, fopen(), setvbuf()

       The Base Definitions volume of POSIX.1‐2017, <stdio.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .