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.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (c) 1993 Michael Haardt
.\" (u31b3hs@pool.informatik.rwth-aachen.de),
.\" Fri Apr 2 11:32:09 MET DST 1993
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
.\" USA.
.\"
.\" Modified Wed Jul 21 19:52:58 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Sun Aug 21 17:40:38 1994 by Rik Faith <faith@cs.unc.edu>
.\"
.TH BRK 2 "21 July 1993" "Linux 0.99.11" "Linux Programmer's Manual"
.SH NAME
brk, sbrk \- change data segment size
.SH SYNOPSIS
.B #include <unistd.h>
.sp
.BI "int brk(void *" end_data_segment );
.sp
.BI "void *sbrk(ptrdiff_t " increment );
.SH DESCRIPTION
.B brk
sets the end of the data segment to the value specified by
.IR end_data_segment .
.I end_datasegment
must be greater than end of the text segment and it must be 16kB before the
end of the stack.
.B sbrk
increments the program's data space by
.I increment
bytes.
.B sbrk
isn't a system call, it is just a C library wrapper.
.SH "RETURN VALUE"
On success,
.B brk
returns zero, and
.B sbrk
returns a pointer to the start of the new area. On error, \-1 is returned,
and
.I errno
is set to
.BR ENOMEM .
.SH "CONFORMING TO"
BSD 4.3
.BR brk " and " sbrk
are not defined in the C Standard and are deliberately excluded from the
POSIX.1 standard (see paragraphs B.1.1.1.3 and B.8.3.3).
.SH "SEE ALSO"
.BR execve "(2), " getrlimit "(2), " malloc (3)
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