CAT(1) General Commands Manual CAT(1)
cat - concatenate and print files
cat [-benstuv] [file ...]
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
-t Print tab characters as `^I'. Implies the -v option to display
-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.
The cat utility exits 0 on success, and >0 if an error occurs.
Print the contents of file1 to the standard output:
$ cat file1
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.
$ cat file1 file2 > file3
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.
$ cat file1 - file2 - file3
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.
The cat utility is compliant with the IEEE Std 1003.1-2008 ("POSIX.1")
The flags [-benstv] are extensions to that specification.
A cat utility appeared in Version 1 AT&T UNIX.
Because of the shell language mechanism used to perform output
redirection, the following command will cause the original data in file1
to be destroyed:
$ cat file1 file2 > file1
To append file2 to file1, instead use:
$ cat file2 >> file1
OpenBSD 6.2 July 10, 2016 OpenBSD 6.2
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