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1 .\" $NetBSD: cat.1,v 1.32 2006/09/23 11:24:44 wiz Exp $
2 .\"
3 .\" Copyright (c) 1989, 1990, 1993
4 .\" The Regents of the University of California. All rights reserved.
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6 .\" This code is derived from software contributed to Berkeley by
7 .\" the Institute of Electrical and Electronics Engineers, Inc.
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33 .\" @(#)cat.1 8.3 (Berkeley) 5/2/95
34 .\"
35 .Dd September 23, 2006
36 .Dt CAT 1
37 .Os
38 .Sh NAME
39 .Nm cat
40 .Nd concatenate and print files
41 .Sh SYNOPSIS
42 .Nm
43 .Op Fl beflnstuv
44 .Op Fl
45 .Op Ar
46 .Sh DESCRIPTION
47 The
48 .Nm
49 utility reads files sequentially, writing them to the standard output.
50 The
51 .Ar file
52 operands are processed in command line order.
53 A single dash represents the standard input,
54 and may appear multiple times in the
55 .Ar file
56 list.
57 .Pp
58 The word
59 .Dq concatenate
60 is just a verbose synonym for
61 .Dq catenate .
62 .Pp
63 The options are as follows:
64 .Bl -tag -width Ds
65 .It Fl b
66 Implies the
67 .Fl n
68 option but doesn't number blank lines.
69 .It Fl e
70 Implies the
71 .Fl v
72 option, and displays a dollar sign
73 .Pq Ql \&$
74 at the end of each line
75 as well.
76 .It Fl f
77 Only attempt to display regular files.
78 .It Fl l
79 Set an exclusive advisory lock on the standard output file descriptor.
80 This lock is set using
81 .Xr fcntl 2
82 with the
83 .Dv F_SETLKW
84 command.
85 If the output file is already locked,
86 .Nm
87 will block until the lock is acquired.
88 .It Fl n
89 Number the output lines, starting at 1.
90 .It Fl s
91 Squeeze multiple adjacent empty lines, causing the output to be
92 single spaced.
93 .It Fl t
94 Implies the
95 .Fl v
96 option, and displays tab characters as
97 .Ql ^I
98 as well.
99 .It Fl u
100 The
101 .Fl u
102 option guarantees that the output is unbuffered.
103 .It Fl v
104 Displays non-printing characters so they are visible.
105 Control characters print as
106 .Ql ^X
107 for control-X; the delete
108 character (octal 0177) prints as
109 .Ql ^? .
110 Non-ascii characters (with the high bit set) are printed as
111 .Ql M-
112 (for meta) followed by the character for the low 7 bits.
113 .El
114 .Sh EXIT STATUS
115 The
116 .Nm
117 utility exits 0 on success, and \*[Gt]0 if an error occurs.
118 .Sh EXAMPLES
119 The command:
120 .Bd -literal -offset indent
121 .Ic cat file1
122 .Ed
123 .Pp
124 will print the contents of
125 .Ar file1
126 to the standard output.
127 .Pp
128 The command:
129 .Bd -literal -offset indent
130 .Ic cat file1 file2 \*[Gt] file3
131 .Ed
132 .Pp
133 will sequentially print the contents of
134 .Ar file1
135 and
136 .Ar file2
137 to the file
138 .Ar file3 ,
139 truncating
140 .Ar file3
141 if it already exists.
142 See the manual page for your shell (i.e.,
143 .Xr sh 1 )
144 for more information on redirection.
145 .Pp
146 The command:
147 .Bd -literal -offset indent
148 .Ic cat file1 - file2 - file3
149 .Ed
150 .Pp
151 will print the contents of
152 .Ar file1 ,
153 print data it receives from the standard input until it receives an
154 .Dv EOF
155 .Pq Sq ^D
156 character, print the contents of
157 .Ar file2 ,
158 read and output contents of the standard input again, then finally output
159 the contents of
160 .Ar file3 .
161 Note that if the standard input referred to a file, the second dash
162 on the command-line would have no effect, since the entire contents of the file
163 would have already been read and printed by
164 .Nm
165 when it encountered the first
166 .Ql \&-
167 operand.
168 .Sh SEE ALSO
169 .Xr head 1 ,
170 .Xr hexdump 1 ,
171 .Xr lpr 1 ,
172 .Xr more 1 ,
173 .Xr pr 1 ,
174 .Xr tail 1 ,
175 .Xr view 1 ,
176 .Xr vis 1 ,
177 .Xr fcntl 2
178 .Rs
179 .%A Rob Pike
180 .%T "UNIX Style, or cat -v Considered Harmful"
181 .%J "USENIX Summer Conference Proceedings"
182 .%D 1983
183 .Re
184 .Sh STANDARDS
185 The
186 .Nm
187 utility is expected to conform to the
188 .St -p1003.2-92
189 specification.
190 .Pp
191 The flags
192 .Op Fl belnstv
193 are extensions to the specification.
194 .Sh HISTORY
195 A
196 .Nm
197 utility appeared in
198 .At v1 .
199 Dennis Ritchie designed and wrote the first man page.
200 It appears to have been
201 .Xr cat 1 .
202 .Sh BUGS
203 Because of the shell language mechanism used to perform output
204 redirection, the command
205 .Dq Li cat file1 file2 \*[Gt] file1
206 will cause the original data in file1 to be destroyed!
207 This is performed by the shell before
208 .Nm
209 is run.