CAT(1) General Commands Manual CAT(1)
cat – concatenate and print files
cat [-belnstuv] [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. If file
is a UNIX domain socket, cat connects to it and then reads it until EOF.
This complements the UNIX domain binding capability available in inetd(8).
The options are as follows:
-b Number the non-blank output lines, starting at 1.
-e Display non-printing characters (see the -v option), and display a
dollar sign (‘$’) at the end of each line.
-l Set an exclusive advisory lock on the standard output file
descriptor. This lock is set using fcntl(2) with the F_SETLKW
command. If the output file is already locked, cat will block
until the lock is acquired.
-n Number the output lines, starting at 1.
-s Squeeze multiple adjacent empty lines, causing the output to be
-t Display non-printing characters (see the -v option), and display
tab characters as ‘^I’.
-u Disable output buffering.
-v Display non-printing characters so they are visible. Control
characters print as ‘^X’ for control-X; the delete 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.
will print the contents of file1 to the standard output.
cat file1 file2 > file3
will 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
will 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.
head(1), more(1), pr(1), sh(1), tail(1), vis(1), zcat(1), fcntl(2),
Rob Pike, “UNIX Style, or cat -v Considered Harmful”, USENIX Summer
Conference Proceedings, 1983.
The cat utility is compliant with the IEEE Std 1003.2-1992 (“POSIX.2”)
The flags [-belnstv] are extensions to the specification.
A cat utility appeared in Version 1 AT&T UNIX. Dennis Ritchie designed and
wrote the first man page. It appears to have been for cat.
Because of the shell language mechanism used to perform output redirection,
the command “cat file1 file2 > file1” will cause the original data in file1
to be destroyed!
The cat utility does not recognize multibyte characters when the -t or -v
option is in effect.
macOS 12.1 January 29, 2013 macOS 12.1