show file content | cat cheat-sheet

What is ‘cat’ ? 🔗

cat is one of the GNU core utils. It is used to print and concatenate files.

There are 2 versions of cat program. The first is GNU cat, and the other is POSIX-compliant cat.

Common usage available in GNU cat and POSIX cat 🔗

Print the contents of a file to the standard output (a.k.a. stdout):

cat path/to/file

Concatenate several files into an output file:

cat path/to/file1 path/to/file2 ... > path/to/output_file

Append several files to an output file:

cat path/to/file1 path/to/file2 ... >> path/to/output_file

Copy the contents of a file into an output file without buffering:

cat -u /dev/tty12 > /dev/tty13

Write the standard input (a.k.a. stdin) to a file:

cat - > path/to/file

Features available ONLY in GNU cat 🔗

Number all output lines:

cat [-n|--number] path/to/file

Display non-printable and whitespace characters (with M- prefix if non-ASCII):

cat [-vte|--show-nonprinting -t -e] path/to/file

For more information, checkout the official documentation: https://www.gnu.org/software/coreutils/manual/html_node/cat-invocation.html , or here https://manned.org/cat.1posix .

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