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. 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.
-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 `^I'.
-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.
The command:
cat file1
will print the contents of file1 to the standard output.
The command:
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 on redirection.
The command:
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), setbuf(3)
Rob Pike, "UNIX Style, or cat -v Considered Harmful", USENIX Summer
Conference Proceedings, 1983.
The cat utility is compliant with the IEEE Std 1003.2-1992 (``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!
FreeBSD 5.2.1 September 15, 2001 FreeBSD 5.2.1 [ Back ] |
