.\" Copyright (c) 2012 Jeremie Le Hen <jlh@FreeBSD.org>
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.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 .