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.\" Copyright (c) 1993
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.\"     @(#)getbsize.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: release/9.1.0/lib/libc/gen/getbsize.3 165903 2007-01-09 00:28:16Z imp $
.\"
.Dd June 4, 1993
.Dt GETBSIZE 3
.Os
.Sh NAME
.Nm getbsize
.Nd get user block size
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft char *
.Fn getbsize "int *headerlenp" "long *blocksizep"
.Sh DESCRIPTION
The
.Fn getbsize
function determines the user's preferred block size based on the value of the
.Dq BLOCKSIZE
environment variable; see
.Xr environ 7
for details on its use and format.
.Pp
The
.Fn getbsize
function returns a pointer to a null-terminated string describing
the block size, something like
.Dq 1K-blocks .
The memory referenced by
.Fa headerlenp
is filled in with the length of the string (not including the
terminating null).
The memory referenced by
.Fa blocksizep
is filled in with block size, in bytes.
.Pp
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.
.Sh SEE ALSO
.Xr df 1 ,
.Xr du 1 ,
.Xr ls 1 ,
.Xr systat 1 ,
.Xr environ 7
.Sh HISTORY
The
.Fn getbsize
function first appeared in
.Bx 4.4 .