CAT(1) | General Commands Manual | CAT(1) |
cat
—
cat |
[-beflnstuv ] [-B
bsize] [- ]
[file ...] |
cat
utility reads files sequentially, writing them
to the standard output. The file operands are processed
in command line order. A single dash represents the standard input, and may
appear multiple times in the file list. If no
file operands are given, standard input is read.
The word “concatenate” is just a verbose synonym for “catenate”.
The options are as follows:
-B
bsize-b
-n
option, but doesn't number blank
lines.-e
-v
option, and displays a dollar sign
(‘$
’) at the end of each line as
well.-f
-l
F_SETLKW
command. If the output file is already
locked, cat
will block until the lock is
acquired.-n
-s
-t
-v
option, and displays tab characters
as ‘^I
’ as well.-u
-u
option guarantees that the output is
unbuffered.-v
^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.cat
utility exits 0 on success,
and >0 if an error occurs.
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 (e.g., 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.
Rob Pike, UNIX Style, or cat -v Considered Harmful, USENIX Summer Conference Proceedings, 1983.
cat
utility is expected to conform to the
IEEE Std 1003.2-1992 (“POSIX.2”)
specification.
The flags [-Bbeflnstv
] are extensions to
the specification.
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).
cat file1 file2 > file1
”
will cause the original data in file1 to be destroyed! This is performed by
the shell before cat
is run.
June 15, 2014 | NetBSD 9.4 |