osx man page for getbsize

GETBSIZE(3)						   BSD Library Functions Manual 					       GETBSIZE(3)

NAME
     getbsize -- get user block size

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     char *
     getbsize(int *headerlenp, long *blocksizep);

DESCRIPTION
     The getbsize() function determines the user's preferred block size based on the value of the ``BLOCKSIZE'' environment variable; see
     environ(7) for details on its use and format.

     The getbsize() function returns a pointer to a null-terminated string describing the block size, something like ``1K-blocks''.  The memory
     referenced by headerlenp is filled in with the length of the string (not including the terminating null).	The memory referenced by
     blocksizep is filled in with block size, in bytes.

     If the user's block size is unreasonable, a warning message is written to standard error and the returned information reflects a block size
     of 512 bytes.

SEE ALSO
     df(1), du(1), ls(1), systat(1), environ(7)

HISTORY
     The getbsize() function first appeared in 4.4BSD.

BSD
								   June 4, 1993 							       BSD