printf(9) - NetBSD Manual Pages

KPRINTF(9)                   NetBSD Kernel Manual                   KPRINTF(9)


NAME

     printf, snprintf, vprintf, vsnprintf, uprintf, ttyprintf, tprintf - ker-
     nel formatted output conversion


SYNOPSIS

     #include <sys/systm.h>

     void
     printf(const char *format, ...);

     int
     snprintf(char *buf, size_t size, const char *format, ...);

     void
     vprintf(const char *format, va_list ap);

     int
     vsnprintf(char *buf, size_t size, const char *format, va_list ap);

     void
     uprintf(const char *format, ...);

     void
     ttyprintf(struct tty *tty, const char *format, ...);

     #include <sys/tprintf.h>

     tpr_t
     tprintf_open(struct proc *p);

     void
     tprintf(tpr_t tpr, const char *format, ...);

     void
     tprintf_close(tpr_t tpr);


DESCRIPTION

     The printf() family of functions allows the kernel to send formatted mes-
     sages to various output devices.  The functions printf() and vprintf()
     send formatted strings to the system console.  The functions snprintf()
     and vsnprintf() write output to a string buffer.  These four functions
     work similarly to their user space counterparts, and are not described in
     detail here.

     The functions uprintf() and ttyprintf() send formatted strings to the
     current process's controlling tty and a specific tty, respectively.

     The tprintf() function sends formatted strings to a process's controlling
     tty, via a handle of type tpr_t.  This allows multiple write operations
     to the tty with a guarantee that the tty will be valid across calls.  A
     handle is acquired by calling tprintf_open() with the target process as
     an argument.  This handle must be closed with a matching call to
     tprintf_close().


RETURN VALUES

     The snprintf() and vsnprintf() functions return the number of characters
     placed in the buffer buf.


SEE ALSO

     printf(1), printf(3), bitmask_snprintf(9)


CODE REFERENCES

     sys/kern/subr_prf.c


HISTORY

     The sprintf() and vsprintf() unsized string formatting functions are sup-
     ported for compatibility only, and are not documented here.  New code
     should use the size-limited snprintf() and vsnprintf() functions instead.

     In NetBSD 1.5 and earlier, printf() supported more format strings than
     the user space printf().  These nonstandard format strings are no longer
     supported.  For the functionality provided by the former %b format
     string, see bitmask_snprintf(9).


BUGS

     The uprintf() and ttyprintf() functions should be used sparingly, if at
     all.  Where multiple lines of output are required to reach a process's
     controlling terminal, tprintf() is preferred.

NetBSD 1.6                     September 1, 1998                             2