`cat`

Concatenate and print files (POSIX)

Syntax:

cat [-c] [-n|-r] [-u] [file...]

Options:

-c: Compress sequences of multiple newline characters into single newlines.
-n: Print line numbers, but don't restart the number for each new file.
-r: Print line numbers, restarting the number for each new file.
-u: Write unbuffered output. Data from the input file(s) is written to the standard output without delay as each file is read.
file: The pathname of an input file. If no files are specified, the standard input is used. If a file is the dash character (-), cat reads from the standard input at that point in the sequence.

Description:

The cat utility reads files in the order you specify and writes their contents to standard output.

Examples:

Write the contents of myfile to standard output:

cat myfile

Concatenate doc1 and doc2 and write the result to doc.all:

cat doc1 doc2 > doc.all

Exit status:

0: All input files were output successfully.
>0: An error occurred.

Caveats:

Because of the shell language mechanism used to perform output redirection, a command such as:

cat doc doc.end > doc

causes the original data in doc to be lost. The file doc is opened for write by the shell, and therefore truncated to zero length, before cat is executed.