text_cmds/cat/cat.1

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  32 .\"     @(#)cat.1       8.3 (Berkeley) 5/2/95
  33 .\" $FreeBSD: src/bin/cat/cat.1,v 1.25 2005/01/16 16:41:55 ru Exp $
  34 .\"
  35 .Dd March 21, 2004
  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 benstuv
  44 .Op Ar
  45 .Sh DESCRIPTION
  46 The
  47 .Nm
  48 utility reads files sequentially, writing them to the standard output.
  49 The
  50 .Ar file
  51 operands are processed in command-line order.
  52 If
  53 .Ar file
  54 is a single dash
  55 .Pq Sq \&-
  56 or absent,
  57 .Nm
  58 reads from the standard input.
  59 If
  60 .Ar file
  61 is a
  62 .Ux
  63 domain socket,
  64 .Nm
  65 connects to it and then reads it until
  66 .Dv EOF .
  67 This complements the
  68 .Ux
  69 domain binding capability available in
  70 .Xr inetd 8 .
  71 .Pp
  72 The options are as follows:
  73 .Bl -tag -width indent
  74 .It Fl b
  75 Number the non-blank output lines, starting at 1.
  76 .It Fl e
  77 Display non-printing characters (see the
  78 .Fl v
  79 option), and display a dollar sign
  80 .Pq Ql \&$
  81 at the end of each line.
  82 .It Fl n
  83 Number the output lines, starting at 1.
  84 .It Fl s
  85 Squeeze multiple adjacent empty lines, causing the output to be
  86 single spaced.
  87 .It Fl t
  88 Display non-printing characters (see the
  89 .Fl v
  90 option), and display tab characters as
  91 .Ql ^I .
  92 .It Fl u
  93 Disable output buffering.
  94 .It Fl v
  95 Display non-printing characters so they are visible.
  96 Control characters print as
  97 .Ql ^X
  98 for control-X; the delete
  99 character (octal 0177) prints as
 100 .Ql ^? .
 101 .Pf Non- Tn ASCII
 102 characters (with the high bit set) are printed as
 103 .Ql M-
 104 (for meta) followed by the character for the low 7 bits.
 105 .El
 106 .Sh EXIT STATUS
 107 .Ex -std
 108 .Sh EXAMPLES
 109 The command:
 110 .Pp
 111 .Dl "cat file1"
 112 .Pp
 113 will print the contents of
 114 .Ar file1
 115 to the standard output.
 116 .Pp
 117 The command:
 118 .Pp
 119 .Dl "cat file1 file2 > file3"
 120 .Pp
 121 will sequentially print the contents of
 122 .Ar file1
 123 and
 124 .Ar file2
 125 to the file
 126 .Ar file3 ,
 127 truncating
 128 .Ar file3
 129 if it already exists.
 130 See the manual page for your shell (i.e.,
 131 .Xr sh 1 )
 132 for more information on redirection.
 133 .Pp
 134 The command:
 135 .Pp
 136 .Dl "cat file1 - file2 - file3"
 137 .Pp
 138 will print the contents of
 139 .Ar file1 ,
 140 print data it receives from the standard input until it receives an
 141 .Dv EOF
 142 .Pq Sq ^D
 143 character, print the contents of
 144 .Ar file2 ,
 145 read and output contents of the standard input again, then finally output
 146 the contents of
 147 .Ar file3 .
 148 Note that if the standard input referred to a file, the second dash
 149 on the command-line would have no effect, since the entire contents of the file
 150 would have already been read and printed by
 151 .Nm
 152 when it encountered the first
 153 .Ql \&-
 154 operand.
 155 .Sh SEE ALSO
 156 .Xr head 1 ,
 157 .Xr more 1 ,
 158 .Xr pr 1 ,
 159 .Xr sh 1 ,
 160 .Xr tail 1 ,
 161 .Xr vis 1 ,
 162 .Xr zcat 1 ,
 163 .Xr setbuf 3
 164 .Rs
 165 .%A Rob Pike
 166 .%T "UNIX Style, or cat -v Considered Harmful"
 167 .%J "USENIX Summer Conference Proceedings"
 168 .%D 1983
 169 .Re
 170 .Sh STANDARDS
 171 The
 172 .Nm
 173 utility is compliant with the
 174 .St -p1003.2-92
 175 specification.
 176 .Pp
 177 The flags
 178 .Op Fl benstv
 179 are extensions to the specification.
 180 .Sh HISTORY
 181 A
 182 .Nm
 183 utility appeared in
 184 .At v1 .
 185 .An Dennis Ritchie
 186 designed and wrote the first man page.
 187 It appears to have been
 188 .Xr cat 1 .
 189 .Sh BUGS
 190 Because of the shell language mechanism used to perform output
 191 redirection, the command
 192 .Dq Li cat file1 file2 > file1
 193 will cause the original data in file1 to be destroyed!
 194 .Pp
 195 The
 196 .Nm
 197 utility does not recognize multibyte characters when the
 198 .Fl t
 199 or
 200 .Fl v
 201 option is in effect.