NetBSD/bin/cat/cat.1

.\"	$NetBSD: cat.1,v 1.29 2003/08/07 09:05:01 agc Exp $
.\"
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.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
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.\"     @(#)cat.1	8.3 (Berkeley) 5/2/95
.\"
.Dd May 2, 1995
.Dt CAT 1
.Os
.Sh NAME
.Nm cat
.Nd concatenate and print files
.Sh SYNOPSIS
.Nm
.Op Fl beflnstuv
.Op Fl
.Op Ar
.Sh DESCRIPTION
The
.Nm
utility reads files sequentially, writing them to the standard output.
The
.Ar file
operands are processed in command line order.
A single dash represents the standard input,
and may appear multiple times in the
.Ar file
list.
.Pp
The word
.Dq concatenate
is just a verbose synonym for
.Dq catenate .
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl b
Implies the
.Fl n
option but doesn't number blank lines.
.It Fl e
Implies the
.Fl v
option, and displays a dollar sign
.Pq Ql \&$
at the end of each line
as well.
.It Fl f
Only attempt to display regular files.
.It Fl l
Set an exclusive advisory lock on the standard output file descriptor.
This lock is set using
.Xr fcntl 2
with the
.Dv F_SETLKW
command.
If the output file is already locked,
.Nm
will block until the lock is acquired.
.It Fl n
Number the output lines, starting at 1.
.It Fl s
Squeeze multiple adjacent empty lines, causing the output to be
single spaced.
.It Fl t
Implies the
.Fl v
option, and displays tab characters as
.Ql ^I
as well.
.It Fl u
The
.Fl u
option guarantees that the output is unbuffered.
.It Fl v
Displays non-printing characters so they are visible.
Control characters print as
.Ql ^X
for control-X; the delete
character (octal 0177) prints as
.Ql ^?
Non-ascii characters (with the high bit set) are printed as
.Ql M-
(for meta) followed by the character for the low 7 bits.
.El
.Sh EXIT STATUS
The
.Nm
utility exits 0 on success, and \*[Gt]0 if an error occurs.
.Sh SEE ALSO
.Xr head 1 ,
.Xr hexdump 1 ,
.Xr lpr 1 ,
.Xr more 1 ,
.Xr pr 1 ,
.Xr tail 1 ,
.Xr view 1 ,
.Xr vis 1 ,
.Xr fcntl 2
.Rs
.%A Rob Pike
.%T "UNIX Style, or cat -v Considered Harmful"
.%J "USENIX Summer Conference Proceedings"
.%D 1983
.Re
.Sh STANDARDS
The
.Nm
utility is expected to conform to the
.St -p1003.2-92
specification.
.Pp
The flags
.Op Fl belnstv
are extensions to the specification.
.Sh HISTORY
A
.Nm
utility appeared in
.At v1 .
Dennis Ritchie designed and wrote the first man page.
It appears to have been
.Xr cat 1 .
.Sh BUGS
Because of the shell language mechanism used to perform output
redirection, the command
.Dq Li cat file1 file2 \*[Gt] file1
will cause the original data in file1 to be destroyed!
This is performed by the shell before
.Nm
is run.