1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)getbsize.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/gen/getbsize.3,v 1.5.2.3 2001/12/14 18:33:51 ru Exp $ 34.\" $DragonFly: src/lib/libc/gen/getbsize.3,v 1.2 2003/06/17 04:26:42 dillon Exp $ 35.\" 36.Dd June 4, 1993 37.Dt GETBSIZE 3 38.Os 39.Sh NAME 40.Nm getbsize 41.Nd get user block size 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In stdlib.h 46.Ft char * 47.Fn getbsize "int *headerlenp" "long *blocksizep" 48.Sh DESCRIPTION 49The 50.Fn getbsize 51function determines the user's preferred block size based on the value of the 52.Dq BLOCKSIZE 53environment variable; see 54.Xr environ 7 55for details on its use and format. 56.Pp 57The 58.Fn getbsize 59function returns a pointer to a null-terminated string describing 60the block size, something like 61.Dq 1K-blocks . 62The memory referenced by 63.Fa headerlenp 64is filled in with the length of the string (not including the 65terminating null). 66The memory referenced by 67.Fa blocksizep 68is filled in with block size, in bytes. 69.Pp 70If the user's block size is unreasonable, a warning message is 71written to standard error and the returned information reflects 72a block size of 512 bytes. 73.Sh SEE ALSO 74.Xr df 1 , 75.Xr du 1 , 76.Xr ls 1 , 77.Xr systat 1 , 78.Xr environ 7 79.Sh HISTORY 80The 81.Fn getbsize 82function first appeared in 83.Bx 4.4 . 84