cat(1) [osx man page]
CAT(1) BSD General Commands Manual CAT(1) NAME
cat -- concatenate and print files SYNOPSIS
cat [-benstuv] [file ...] DESCRIPTION
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 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. EXIT STATUS
The cat utility exits 0 on success, and >0 if an error occurs. EXAMPLES
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 con- tents 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. SEE ALSO
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. STANDARDS
The cat utility is compliant with the IEEE Std 1003.2-1992 (``POSIX.2'') specification. The flags [-benstv] are extensions to the specification. HISTORY
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). BUGS
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. BSD
March 21, 2004 BSD
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cat(1) General Commands Manual cat(1) NAME
cat - concatenate, copy, and print files SYNOPSIS
file ... DESCRIPTION
reads each file in sequence and writes it on the standard output. Thus: prints file on the default standard output device; concatenates file1 and file2, and places the result in file3. If is appears as a file argument, uses standard input. To combine standard input and other files, use a combination of and file arguments. Options recognizes the following options: Omit line numbers from blank lines when option is specified. If this option is specified, the option is automatically selected. Print a character at the end of each line (prior to the new-line). If this option is specified, the option is automatically selected. Display output lines preceded by line numbers, numbered sequentially from 1. Replace multiple consecutive empty lines with one empty line, so that there is never more than one empty line between lines containing characters. Silent option. suppresses error messages about non-existent files, identical input and output, and write errors. Normally, input and output files cannot have identical names unless the file is a special file. Print each tab character as and form feed character as If this option is specified, the option is automatically selected. Do not buffer output (handle character-by-character). Normally, output is buffered. Cause non-printing characters (with the exception of tabs, new-lines and form-feeds) to be printed visibly. Control characters are printed using the form (Ctrl-X), and the DEL character (octal 0177) is printed as (see ascii(5)). Single-byte control characters whose most signifi- cant bit is set, are printed using the form where x is the character specified by the seven low order bits. All other non- printing characters are printed as where x is the character specified by the seven low order bits. This option is influenced by the environment variable and its corresponding code set. EXTERNAL INFLUENCES
Environment Variables provides a default value for the internationalization variables that are unset or null. If is unset or null, the default value of "C" (see lang(5)) is used. If any of the internationalization variables contains an invalid setting, will behave as if all internationalization variables are set to "C". See environ(5). If set to a non-empty string value, overrides the values of all the other internationalization variables. determines the interpretation of text as single and/or multi-byte characters, the classification of characters as printable, and the char- acters matched by character class expressions in regular expressions. determines the locale that should be used to affect the format and contents of diagnostic messages written to standard error and informa- tive messages written to standard output. determines the location of message catalogues for the processing of International Code Set Support Single- and multi-byte character code sets are supported. RETURN VALUE
Exit values are: 0 Successful completion. >0 Error condition occurred. EXAMPLES
To create a zero-length file, use any of the following: The following prints for all the occurrences of tab character in file1 To suppress error messages about files that do not exist, use: If file2 does not exist, the above command concatenates file1 and file3 without reporting the error on file2. The result is the same if option is not used, except that displays the error message. To view non-printable characters in file2, use: WARNINGS
Command formats such as overwrites the data in file1 before the concatenation begins, thus destroying the file. Therefore, be careful when using shell special characters. SEE ALSO
cp(1), more(1), pg(1), pr(1), rmnl(1), ssp(1). STANDARDS CONFORMANCE
cat(1)