CAT(1) BSD Reference 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. The options are as follows: -b Implies the -n option but doesn't count blank lines. -e Implies the -v option and also prints 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 un- til the lock is acquired. -n Number the output lines, starting at 1. -s Squeeze multiple adjacent empty lines, causing the output to be single spaced. -t Implies the -v option and also prints tab characters as '^I'. -u The output is guaranteed to be unbuffered (see setbuf(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 tab character, control-I, can be made visible via the -t option. 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 or >0 if an error occurred.
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 in- put 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), fcntl(2), 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 [-belnstv] are extensions to the specification.
A cat utility appeared in Version 1 AT&T UNIX. The -l option was added from NetBSD in MirOS #11.
Because of the shell language mechanism used to perform output redirec- tion, the command cat file1 file2 > file1 will cause the original data in file1 to be destroyed! MirOS BSD #10-current May 20, 2012 1
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