cat reads each file in sequence and writes it on
the standard output. If no input file is given, or if a single dash
(-) is given, cat reads from the standard input. The
options are:
-s
Suppresses warnings about nonexistent files.
-u
Causes the output to be unbuffered.
-v
Causes non-printing characters (with the exception of tabs,
newlines, and form feeds) to be displayed. Control characters are
displayed as ^X (<Ctrl>x), where X is
the key pressed with the <Ctrl> key (for example, <Ctrl>m is
displayed as ^M). The <Del> character (octal 0177) is
printed as ^?. Non-ASCII characters (with the high bit
set) are printed as M -x, where x is
the character specified by the seven low order bits.
-t
Causes tabs to be printed as ^I
and form feeds as ^L. This option is ignored if the
-v option is not specified.
-e
Causes a ``$'' character to be printed at the end of each line
(prior to the new-line). This option is ignored if the -v
option is not set.
Exit values
cat returns the following values:
0
all input files were output successfully
>0
an error occurred
Examples
The following example displays file on the standard
output:
cat file
The following example concatenates file1 and
file2 and places the result in file3:
cat file1 file2 >file3
The following example concatenates file1 and appends it to
file2:
cat file1 >> file2
Warning
Command lines such as:
cat file1 file2 > file1
will cause the original data in file1 to be lost;
therefore, you must be careful when using special shell characters.