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NAME

cat — concatenate and print files

SYNOPSIS

DESCRIPTION

The cat utility reads files sequentially, writing them to the standard output. The file operands are processed in command-line order. If file is a single dash (‘-’) or absent, cat reads from the standard input.

The options are as follows:

-b

Number the lines, but don't count blank lines.

-e

Print a dollar sign (‘$’) at the end of each line. Implies the -v option to display non-printing characters.

-n

Number the output lines, starting at 1.

-s

Squeeze multiple adjacent empty lines, causing the output to be single spaced.

-t

Print tab characters as ‘^I’. Implies the -v option to display non-printing characters.

-u

The output is guaranteed to be unbuffered (see setvbuf(3)).

-v

Displays non-printing characters so they are visible. Control characters print as ‘^X’ for control-X, with the exception of the tab and EOL characters, which are displayed normally. The DEL character (octal 0177) prints as ‘^?’. Non-ASCII characters (with the high bit set) are printed as ‘M-’ (for meta) followed by the character for the low 7 bits.

EXIT STATUS

The cat utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

Print the contents of file1 to the standard output:

Sequentially print the contents of file1 and file2 to the file file3, truncating file3 if it already exists. See the manual page for your shell (e.g., sh(1)) for more information on redirection.

Print the contents of file1, print data it receives from the standard input until it receives an EOF (‘^D’) character, print the contents of file2, read and output contents of the standard input again, then finally output the contents of 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 cat when it encountered the first ‘-’ operand.

SEE ALSO

head(1), less(1), more(1), pr(1), sh(1), tail(1), vis(1), setvbuf(3)

Rob Pike, UNIX Style, or cat -v Considered Harmful, USENIX Summer Conference Proceedings, 1983.

STANDARDS

The cat utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification.

The flags [-benstv] are extensions to that specification.

HISTORY

A cat utility appeared in Version 1 AT&T UNIX.

CAVEATS

Because of the shell language mechanism used to perform output redirection, the following command will cause the original data in file1 to be destroyed:

To append file2 to file1, instead use: