CAT(1) BSD 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 op-
erands 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
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.
-n Number the output lines, starting at 1.
-s Squeeze multiple adjacent empty lines, causing the output to be single spaced.
-t Display non-printing characters (see the -v option), and display tab characters as
-u The -u option guarantees that the output is unbuffered.
-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 (i.e., sh(1)) for more information
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 stan-
dard 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), setbuf(3)
Rob Pike, "UNIX Style, or cat -v Considered Harmful", USENIX Summer Conference Proceedings,
The cat utility is compliant with the IEEE Std 1003.2-1992 (``POSIX.2'') specification.
The flags [-benstv] 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 cat(1).
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!
BSD September 15, 2001 BSD