Create a File With `cat`

When you combine cat (concatenate) with > (output redirection), you can create and write to a file from the command line.

$ cat > test.txt

Hit enter after the file name, and your terminal will wait for input. End the file with CTRL + D.

$ cat > test.txt
one
two
three
$ cat test.txt
one
two
three

>> works, too; appending to the file as expected.