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While here add CAVEAT section and promote the use of printf(1) Reviewed by: gbe@, imp@ Approved by: manpages (gbe) Differential Revision: https://reviews.freebsd.org/D43493
137 lines
3.7 KiB
Groff
137 lines
3.7 KiB
Groff
.\"-
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.\" Copyright (c) 1990, 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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.\" the Institute of Electrical and Electronics Engineers, Inc.
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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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.Dd October 5, 2016
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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 write arguments to the standard output
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.Sh SYNOPSIS
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.Nm
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.Op Fl n
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.Op Ar string ...
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.Sh DESCRIPTION
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The
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.Nm
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utility writes any specified operands, separated by single blank
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.Pq Ql "\ "
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characters and followed by a newline
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.Pq Ql \en
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character, to the standard
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output.
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.Pp
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The following option is available:
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.Bl -tag -width flag
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.It Fl n
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Do not print the trailing newline character.
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.El
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.Pp
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The end-of-options marker
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.Fl Fl
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is not recognized and written literally.
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.Pp
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The newline may also be suppressed by appending
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.Ql \ec
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to the end of the string, as is done
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by iBCS2 compatible systems.
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Note that the
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.Fl n
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option as well as the effect of
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.Ql \ec
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are implementation-defined in
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.St -p1003.1-2001
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as amended by Cor.\& 1-2002.
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For portability,
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.Nm
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should only be used if the first argument does not start with a hyphen
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.Pq Ql "-"
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and does not contain any backslashes
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.Pq Ql "\e" .
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If this is not sufficient,
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.Xr printf 1
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should be used.
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.Pp
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Most shells provide a builtin
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.Nm
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command which tends to differ from this utility
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in the treatment of options and backslashes.
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Consult the
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.Xr builtin 1
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manual page.
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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Special treatment of options and backslashes:
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.Bd -literal -offset indent
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$ /bin/echo "-hello\\tworld"
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-hello\tworld
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.Ed
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.Pp
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Avoid new line character:
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.Bd -literal -offset indent
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$ /bin/echo -n hello;/bin/echo world
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helloworld
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.Ed
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.Pp
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Or to achieve the same result:
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.Bd -literal -offset indent
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$ /bin/echo "hello\\c";/bin/echo world
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helloworld
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.Ed
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.Sh SEE ALSO
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.Xr builtin 1 ,
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.Xr csh 1 ,
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.Xr printf 1 ,
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.Xr sh 1
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.Sh STANDARDS
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The
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.Nm
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utility conforms to
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.St -p1003.1-2001
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as amended by Cor.\& 1-2002.
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.At v2 .
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.Sh CAVEATS
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The
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.Nm
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command behaves differently with regards to the built-in
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.Nm
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shell command in a number of ways including escaped characters handling.
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It also differs in behavior between different systems hence complicating writing
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portable scripts.
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It is advised to use the
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.Xr printf 1
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command to avoid these shortcomings.
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