You have many files in a directory that you want to combine into one file. You could open them one at a time and copy/paste them into a new file but who has time for that!

Use the cat (short for concatenate) command, with shell redirection (>>) into your output file.

First, open a shell and cd into the directory where the files reside and list the contents, for example

Next type "cat filename*.txt >> output file" and hit enter

Explanation: "cat" is the command "filename*" tells cat to concatenate all files that start with "filename" and the ">>" tells cat to output the results to a new file, and finally "output" is the name of the resultant file name.

Example screenshot:

After running the cat command and listing the directory, you'll see the new file, in this case numbers.txt. And if you list the directory with the -al flag you'll see the file size is much larger than any single file.