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.\" Copyright (c) 2012 Jeremie Le Hen <jlh@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code and documentation must retain the above
.\" copyright notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd April 28, 2012
.Dt STDBUF 1
.Os
.Sh NAME
.Nm stdbuf
.Nd change standard streams initial buffering
.Sh SYNOPSIS
.Nm
.Op Fl e Ar bufdef
.Op Fl i Ar bufdef
.Op Fl o Ar bufdef
.Op Ar command Op ...
.Sh DESCRIPTION
.Nm
is used to change the initial buffering of standard input,
standard output and/or standard error streams for
.Ar command .
It relies on
.Xr libstdbuf 3
which is loaded and configured by
.Nm
through environment variables.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl e Ar bufdef
Set initial buffering of the standard error stream for
.Ar command
as defined by
.Ar bufdef
.Pq see Sx BUFFER DEFINITION .
.It Fl i Ar bufdef
Set initial buffering of the standard input stream for
.Ar command
as defined by
.Ar bufdef
.Pq see Sx BUFFER DEFINITION .
.It Fl o Ar bufdef
Set initial buffering of the standard output stream for
.Ar command
as defined by
.Ar bufdef
.Pq see Sx BUFFER DEFINITION .
.El
.Sh BUFFER DEFINITION
Buffer definition is the same as in
.Xr libstdbuf 3 :
.Bl -tag -width size -offset indent
.It Qq 0
unbuffered
.It Qq L
line buffered
.It Qq B
fully buffered with the default buffer size
.It Ar size
fully buffered with a buffer of
.Ar size
bytes (suffixes 'k', 'M' and 'G' are accepted)
.El
.Sh EXAMPLES
In the following example, the stdout stream of the
.Xr awk 1
command
will be fully buffered by default because it does not refer
to a terminal.
.Nm
is used to force it to be line-buffered so
.Xr vmstat 8 Ns 's
output will not stall until the full buffer fills.
.Bd -literal -offset indent
# vmstat 1 | stdbuf -o L awk '$2 > 1 || $3 > 1' | cat -n
.Ed
.Sh SEE ALSO
.Xr libstdbuf 3 ,
.Xr setvbuf 3
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 8.4 .
.Sh AUTHORS
.An -nosplit
The original idea of the
.Nm
command comes from
.An Padraig Brady
who implemented it in the GNU coreutils.
.An Jeremie Le Hen
implemented it on
.Fx .
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