xref: /netbsd-src/bin/sh/bltin/echo.1 (revision 01869ca4d24a86379a68731bf9706a9f0820fe4e)

.\"	$NetBSD: echo.1,v 1.14 2017/07/03 21:33:24 wiz Exp $
.\"
.\" Copyright (c) 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Kenneth Almquist.
.\" Copyright 1989 by Kenneth Almquist
.\"
.\" 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 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.
.\" 3. 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
.\"
.\"	@(#)echo.1	8.1 (Berkeley) 5/31/93
.\"
.Dd May 31, 1993
.Dt ECHO 1
.Os
.Sh NAME
.Nm echo
.Nd produce message in a shell script
.Sh SYNOPSIS
.Nm
.Op Fl n | Fl e
.Ar args ...
.Sh DESCRIPTION
.Nm
prints its arguments on the standard output, separated by spaces.
Unless the
.Fl n
option is present, a newline is output following the arguments.
The
.Fl e
option causes
.Nm
to treat the escape sequences specially, as described in the following
paragraph.
The
.Fl e
option is the default, and is provided solely for compatibility with
other systems.
Only one of the options
.Fl n
and
.Fl e
may be given.
.Pp
If any of the following sequences of characters is encountered during
output, the sequence is not output.  Instead, the specified action is
performed:
.Bl -tag -width indent
.It Li \eb
A backspace character is output.
.It Li \ec
Subsequent output is suppressed.  This is normally used at the end of the
last argument to suppress the trailing newline that
.Nm
would otherwise output.
.It Li \ef
Output a form feed.
.It Li \en
Output a newline character.
.It Li \er
Output a carriage return.
.It Li \et
Output a (horizontal) tab character.
.It Li \ev
Output a vertical tab.
.It Li \e0 Ns Ar digits
Output the character whose value is given by zero to three digits.
If there are zero digits, a nul character is output.
.It Li \e\e
Output a backslash.
.El
.Sh HINTS
Remember that backslash is special to the shell and needs to be escaped.
To output a message to standard error, say
.Pp
.D1  echo message >&2
.Sh BUGS
The octal character escape mechanism
.Pq Li \e0 Ns Ar digits
differs from the
C language mechanism.
.Pp
There is no way to force
.Nm
to treat its arguments literally, rather than interpreting them as
options and escape sequences.