dprintf, vdprintf − print to a file descriptor

#define _GNU_SOURCE
#include <stdio.h>

int dprintf(int fd, const char *format, ...);

int vdprintf(int fd, const char *format, va_list ap);

The functions dprintf and vdprintf (as found in the glibc2 library) are exact analogues of fprintf and vfprintf, except that they output to a file descriptor fd instead of to a given stream.

These functions are GNU extensions, not in C or POSIX. Clearly, the names were badly chosen. Many systems (like MacOS) have incompatible functions called dprintf, usually some debugging version of printf, perhaps with a prototype like

void dprintf (int level, const char *format, ...);

where the first parameter is a debugging level (and output is to stderr). Moreover, dprintf (or DPRINTF) is also a popular macro name for a debugging printf. So, probably, it is better to avoid this function in programs intended to be portable.

A better name would have been fdprintf.

printf(3)