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freebsd/lib/libc/gen/getbsize.3

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.\" Copyright (c) 1993
.\" The Regents of the University of California. All rights reserved.
.\"
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.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" SUCH DAMAGE.
.\"
.\" @(#)getbsize.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.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 .