man3/dprintf.3

   1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
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  23 .\" Text fragments inspired by Martin Schulze <joey@infodrom.org>.
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  25 .TH DPRINTF 3 2001-12-18 "GNU" "Linux Programmer's Manual"
  26 .SH NAME
  27 dprintf, vdprintf \- print to a file descriptor
  28 .SH SYNOPSIS
  29 .B #define _GNU_SOURCE
  30 .br
  31 .B #include <stdio.h>
  32 .sp
  33 .BI "int dprintf(int " fd ", const char *" format ", ...);"
  34 .sp
  35 .BI "int vdprintf(int " fd ", const char *" format ", va_list " ap );
  36 .SH DESCRIPTION
  37 The functions
  38 .BR dprintf ()
  39 and
  40 .BR vdprintf ()
  41 (as found in the glibc2 library) are exact analogues of
  42 .BR fprintf (3)
  43 and
  44 .BR vfprintf (3),
  45 except that they output to a file descriptor
  46 .I fd
  47 instead of to a given stream.
  48 .SH "CONFORMING TO"
  49 These functions are GNU extensions.
  50 .SH NOTES
  51 These functions are GNU extensions, not in C or POSIX.
  52 Clearly, the names were badly chosen.
  53 Many systems (like MacOS) have incompatible functions called
  54 .BR dprintf (),
  55 usually some debugging version of
  56 .BR printf (3),
  57 perhaps with a prototype like
  58
  59 .BI "void dprintf(int level, const char *" format ", ...);"
  60
  61 where the first parameter is a debugging level (and output is to
  62 .IR stderr ).
  63 Moreover,
  64 .BR dprintf ()
  65 (or
  66 .BR DPRINTF )
  67 is also a popular macro name for a debugging printf.
  68 So, probably, it is better to avoid this function in programs
  69 intended to be portable.
  70
  71 A better name would have been
  72 .BR fdprintf ().
  73 .SH "SEE ALSO"
  74 .BR printf (3),
  75 .BR feature_test_macros (7)