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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd June 11, 2017 29.Dt GETBSIZE 3 30.Os 31.Sh NAME 32.Nm getbsize 33.Nd get preferred block size 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In stdlib.h 38.Ft char * 39.Fn getbsize "int *headerlenp" "long *blocksizep" 40.Sh DESCRIPTION 41The 42.Fn getbsize 43function returns a preferred block size for reporting by system utilities 44.Xr df 1 , 45.Xr du 1 46and 47.Xr ls 1 , 48based on the value of the 49.Ev BLOCKSIZE 50environment variable. 51.Ev BLOCKSIZE 52may be specified directly in bytes, or in multiples of a kilobyte by 53specifying a number followed by ``K'' or ``k'', in multiples of a 54megabyte by specifying a number followed by ``M'' or ``m'' or in 55multiples of a gigabyte by specifying a number followed by ``G'' or 56``g''. 57Multiples must be integers. 58.Pp 59Valid values of 60.Ev BLOCKSIZE 61are 512 bytes to 1 gigabyte. 62Sizes less than 512 bytes are rounded up to 512 bytes, and sizes 63greater than 1 GB are rounded down to 1 GB. 64In each case 65.Fn getbsize 66produces a warning message via 67.Xr warnx 3 . 68.Pp 69The 70.Fn getbsize 71function returns a pointer to a null-terminated string describing 72the block size, something like 73.Dq 1K-blocks . 74The memory referenced by 75.Fa headerlenp 76is filled in with the length of the string (not including the 77terminating null). 78The memory referenced by 79.Fa blocksizep 80is filled in with block size, in bytes. 81.Sh SEE ALSO 82.Xr df 1 , 83.Xr du 1 , 84.Xr ls 1 , 85.Xr systat 1 , 86.Xr environ 7 87.Sh HISTORY 88The 89.Fn getbsize 90function first appeared in 91.Bx 4.4 . 92