110 lines
3.5 KiB
Groff
110 lines
3.5 KiB
Groff
.\" $NetBSD: echo.1,v 1.13 2003/08/07 09:05:40 agc Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Kenneth Almquist.
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.\" Copyright 1989 by Kenneth Almquist
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)echo.1 8.1 (Berkeley) 5/31/93
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.\"
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.Dd May 31, 1993
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.Dt ECHO 1
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.Os
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.Sh NAME
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.Nm echo
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.Nd produce message in a shell script
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.Sh SYNOPSIS
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.Nm
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.Op Fl n | Fl e
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.Ar args ...
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.Sh DESCRIPTION
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.Nm
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prints its arguments on the standard output, separated by spaces.
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Unless the
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.Fl n
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option is present, a newline is output following the arguments.
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The
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.Fl e
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option causes
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.Nm
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to treat the escape sequences specially, as described in the following
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paragraph.
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The
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.Fl e
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option is the default, and is provided solely for compatibility with
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other systems.
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Only one of the options
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.Fl n
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and
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.Fl e
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may be given.
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.Pp
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If any of the following sequences of characters is encountered during
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output, the sequence is not output. Instead, the specified action is
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performed:
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.Bl -tag -width indent
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.It Li \eb
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A backspace character is output.
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.It Li \ec
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Subsequent output is suppressed. This is normally used at the end of the
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last argument to suppress the trailing newline that
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.Nm
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would otherwise output.
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.It Li \ef
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Output a form feed.
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.It Li \en
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Output a newline character.
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.It Li \er
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Output a carriage return.
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.It Li \et
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Output a (horizontal) tab character.
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.It Li \ev
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Output a vertical tab.
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.It Li \e0 Ns Ar digits
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Output the character whose value is given by zero to three digits.
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If there are zero digits, a nul character is output.
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.It Li \e\e
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Output a backslash.
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.El
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.Sh HINTS
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Remember that backslash is special to the shell and needs to be escaped.
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To output a message to standard error, say
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.Pp
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.D1 echo message \*[Gt]\*[Am]2
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.Sh BUGS
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The octal character escape mechanism
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.Pq Li \e0 Ns Ar digits
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differs from the
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C language mechanism.
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.Pp
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There is no way to force
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.Nm
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to treat its arguments literally, rather than interpreting them as
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options and escape sequences.
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