.\"	$OpenBSD: expand.1,v 1.3 1998/09/23 04:32:39 aaron Exp $
.\"	$NetBSD: expand.1,v 1.3 1995/09/02 06:19:45 jtc Exp $
.\"
.\" Copyright (c) 1980, 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\"	@(#)expand.1	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt EXPAND 1
.Os BSD 4
.Sh NAME
.Nm expand ,
.Nm unexpand
.Nd expand tabs to spaces, and vice versa
.Sh SYNOPSIS
.Nm expand
.Op Fl Ns Ar tabstop
.Op Fl Ns Ar tab1 , tab2 , ... , tabn
.Ar file Op Ar ...
.Nm unexpand
.Op Fl a
.Ar file Op Ar ...
.Sh DESCRIPTION
.Nm expand
processes the named files or the standard input writing
the standard output with tabs changed into blanks.
Backspace characters are preserved into the output and decrement
the column count for tab calculations.
.Nm expand
is useful for pre-processing character files
(before sorting, looking at specific columns, etc.) that
contain tabs.
.Pp
If a single
.Ar tabstop
argument is given, tabs are set
.Ar tabstop
spaces apart instead of the default 8.
If multiple tabstops are given then the tabs are set at those
specific columns.
.Pp
.Nm unexpand
puts tabs back into the data from the standard input or the named
files and writes the result on the standard output.
.Pp
Option (with
.Nm unexpand
only):
.Bl -tag -width flag
.It Fl a
By default, only leading blanks and tabs
are reconverted to maximal strings of tabs.  If the
.Fl a
option is given, tabs are inserted whenever they would compress the
resultant file by replacing two or more characters.
.El
.Sh HISTORY
The
.Nm expand
command appeared in
.Bx 3.0 .