- concatenate and display files
cat [-nbsuvet] [file]...
The cat utility reads each file in sequence and writes it on the standard output. Thus:
example% cat file
prints file on your terminal, and:
example% cat file1 file2 >file3
concatenates file1 and file2, and writes the results in file3. If no input file is given, cat reads from the standard input file.
The following options are supported:
Precede each line output with its line number.
Number the lines, as -n, but omit the line numbers from blank lines.
The output is not buffered. (The default is buffered output.)
cat is silent about non-existent files.
Non-printing characters (with the exception of tabs, new-lines and form-feeds) are printed visibly. ASCII control characters (octal 000 - 037) are printed as ^n, where n is the corresponding ASCII character in the range octal 100 - 137 (@, A, B, C, . . ., X, Y, Z, [, \, ], ^, and _); the DEL character (octal 0177) is printed ^?. Other non-printable characters are printed as M-x, where x is the ASCII character specified by the low-order seven bits.
When used with the -v option, the following options may be used:
A $ character will be printed at the end of each line (prior to the new-line).
Tabs will be printed as ^I's and formfeeds to be printed as ^L's.
The -e and -t options are ignored if the -v option is not specified.
The following operand is supported:
A path name of an input file. If no file is specified, the standard input is used. If file is ` - ', cat will read from the standard input at that point in the sequence. cat will not close and reopen standard input when it is referenced in this way, but will accept multiple occurrences of ` - ' as file.
See largefile(5) for the description of the behavior of cat when encountering files greater than or equal to 2 Gbyte ( 231 bytes).
Example 1 Concatenating a file
The following command:
example% cat myfile
writes the contents of the file myfile to standard output.
Example 2 Concatenating two files into one
The following command:
example% cat doc1 doc2 > doc.all
concatenates the files doc1 and doc2 and writes the result to doc.all.
Example 3 Concatenating two arbitrary pieces of input with a single invocation
example% cat start - middle - end > file
when standard input is a terminal, gets two arbitrary pieces of input from the terminal with a single invocation of cat. Note, however, that if standard input is a regular file, this would be equivalent to the command:
cat start - middle /dev/null end > file
because the entire contents of the file would be consumed by cat the first time ` - ' was used as a file operand and an end-of-file condition would be detected immediately when ` - ' was referenced the second time.
See environ(5) for descriptions of the following environment variables that affect the execution of cat: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
All input files were output successfully.
An error occurred.
See attributes(5) for descriptions of the following attributes:
Redirecting the output of cat onto one of the files being read will cause the loss of the data originally in the file being read. For example,
example% cat filename1 filename2 >filename1
causes the original data in filename1 to be lost.