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@(#)cat.1 8.3 (Berkeley) 5/2/95
$FreeBSD: releng/10.2/bin/cat/cat.1 246090 2013-01-29 20:01:47Z joel $
.Dd January 29, 2013 .Dt CAT 1 .Os .Sh NAME .Nm cat .Nd concatenate and print files .Sh SYNOPSIS .Nm .Op Fl belnstuv .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. If .Ar file is a single dash
q Sq Fl or absent, .Nm reads from the standard input. If .Ar file is a x domain socket, .Nm connects to it and then reads it until .Dv EOF . This complements the x domain binding capability available in .Xr inetd 8 .
p The options are as follows: l -tag -width indent t Fl b Number the non-blank output lines, starting at 1. t Fl e Display non-printing characters (see the .Fl v option), and display a dollar sign
q Ql $ at the end of each line. t 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. t Fl n Number the output lines, starting at 1. t Fl s Squeeze multiple adjacent empty lines, causing the output to be single spaced. t Fl t Display non-printing characters (see the .Fl v option), and display tab characters as .Ql ^I . t Fl u Disable output buffering. t Fl v Display non-printing characters so they are visible. Control characters print as .Ql ^X for control-X; the delete character (octal 0177) prints as .Ql ^? .
f Non- Tn 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 .Ex -std .Sh EXAMPLES The command:
p .Dl "cat file1"
p will print the contents of
a file1 to the standard output.
p The command:
p .Dl "cat file1 file2 > file3"
p will sequentially print the contents of
a file1 and
a file2 to the file
a file3 , truncating
a file3 if it already exists. See the manual page for your shell (e.g., .Xr sh 1 ) for more information on redirection.
p The command:
p .Dl "cat file1 - file2 - file3"
p will print the contents of
a file1 , print data it receives from the standard input until it receives an .Dv EOF
q Sq ^D character, print the contents of
a file2 , read and output contents of the standard input again, then finally output the contents of
a file3 . Note that if the standard input referred to a file, the second dash on the command-line would have no effect, since the entire contents of the file would have already been read and printed by .Nm when it encountered the first .Sq Fl operand. .Sh SEE ALSO .Xr head 1 , .Xr more 1 , .Xr pr 1 , .Xr sh 1 , .Xr tail 1 , .Xr vis 1 , .Xr zcat 1 , .Xr fcntl 2 , .Xr setbuf 3 .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 compliant with the .St -p1003.2-92 specification.
p The flags .Op Fl belnstv are extensions to the specification. .Sh HISTORY A .Nm utility appeared in .At v1 . .An 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 > file1 will cause the original data in
a file1 to be destroyed!
p The .Nm utility does not recognize multibyte characters when the .Fl t or .Fl v option is in effect.