set an exclusive advisory lock on stdout. This will be used to guarantee orderly writing to METALOG. Sponsored by: DARPA, AFRL Obtained from: NetBSD (mason)
215 lines
5.1 KiB
Groff
215 lines
5.1 KiB
Groff
.\"-
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.\" Copyright (c) 1989, 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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.\" 4. 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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.\" @(#)cat.1 8.3 (Berkeley) 5/2/95
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.\" $FreeBSD$
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.\"
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.Dd Jaunary 29, 2013
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.Dt CAT 1
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.Os
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.Sh NAME
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.Nm cat
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.Nd concatenate and print files
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.Sh SYNOPSIS
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.Nm
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.Op Fl belnstuv
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.Op Ar
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.Sh DESCRIPTION
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The
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.Nm
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utility reads files sequentially, writing them to the standard output.
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The
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.Ar file
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operands are processed in command-line order.
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If
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.Ar file
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is a single dash
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.Pq Sq Fl
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or absent,
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.Nm
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reads from the standard input.
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If
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.Ar file
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is a
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.Ux
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domain socket,
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.Nm
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connects to it and then reads it until
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.Dv EOF .
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This complements the
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.Ux
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domain binding capability available in
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.Xr inetd 8 .
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl b
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Number the non-blank output lines, starting at 1.
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.It Fl e
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Display non-printing characters (see the
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.Fl v
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option), and display a dollar sign
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.Pq Ql \&$
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at the end of each line.
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.It Fl l
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Set an exclusive advisory lock on the standard output file descriptor.
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This lock is set using
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.Xr fcntl 2
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with the
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.Dv F_SETLKW
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command.
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If the output file is already locked,
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.Nm
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will block until the lock is acquired.
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.It Fl n
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Number the output lines, starting at 1.
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.It Fl s
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Squeeze multiple adjacent empty lines, causing the output to be
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single spaced.
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.It Fl t
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Display non-printing characters (see the
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.Fl v
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option), and display tab characters as
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.Ql ^I .
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.It Fl u
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Disable output buffering.
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.It Fl v
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Display non-printing characters so they are visible.
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Control characters print as
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.Ql ^X
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for control-X; the delete
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character (octal 0177) prints as
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.Ql ^? .
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.Pf Non- Tn ASCII
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characters (with the high bit set) are printed as
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.Ql M-
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(for meta) followed by the character for the low 7 bits.
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.El
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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The command:
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.Pp
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.Dl "cat file1"
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.Pp
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will print the contents of
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.Pa file1
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to the standard output.
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.Pp
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The command:
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.Pp
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.Dl "cat file1 file2 > file3"
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.Pp
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will sequentially print the contents of
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.Pa file1
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and
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.Pa file2
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to the file
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.Pa file3 ,
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truncating
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.Pa file3
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if it already exists.
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See the manual page for your shell (e.g.,
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.Xr sh 1 )
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for more information on redirection.
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.Pp
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The command:
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.Pp
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.Dl "cat file1 - file2 - file3"
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.Pp
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will print the contents of
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.Pa file1 ,
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print data it receives from the standard input until it receives an
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.Dv EOF
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.Pq Sq ^D
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character, print the contents of
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.Pa file2 ,
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read and output contents of the standard input again, then finally output
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the contents of
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.Pa file3 .
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Note that if the standard input referred to a file, the second dash
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on the command-line would have no effect, since the entire contents of the file
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would have already been read and printed by
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.Nm
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when it encountered the first
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.Sq Fl
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operand.
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.Sh SEE ALSO
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.Xr head 1 ,
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.Xr more 1 ,
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.Xr pr 1 ,
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.Xr sh 1 ,
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.Xr tail 1 ,
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.Xr vis 1 ,
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.Xr zcat 1 ,
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.Xr fcntl 2 ,
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.Xr setbuf 3
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.Rs
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.%A Rob Pike
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.%T "UNIX Style, or cat -v Considered Harmful"
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.%J "USENIX Summer Conference Proceedings"
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.%D 1983
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.Re
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.Sh STANDARDS
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The
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.Nm
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utility is compliant with the
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.St -p1003.2-92
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specification.
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.Pp
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The flags
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.Op Fl belnstv
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are extensions to the specification.
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v1 .
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.An Dennis Ritchie
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designed and wrote the first man page.
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It appears to have been
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.Xr cat 1 .
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.Sh BUGS
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Because of the shell language mechanism used to perform output
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redirection, the command
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.Dq Li cat file1 file2 > file1
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will cause the original data in
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.Pa file1
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to be destroyed!
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.Pp
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The
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.Nm
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utility does not recognize multibyte characters when the
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.Fl t
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or
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.Fl v
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option is in effect.
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