Output is the screen . If the destination file does not exist, it is created. File2' will cause 'file2' to be overwriten. The '-a' option causes output to append instead of overwrite. Pipes are used to pass data from one program to the next.
Filters read data, perform some operation on the data, and output the result.
The 'cat' command can be used to copy data from one file to another. The 'grep' command will search for all the lines in a collection of data that contain a specified pattern and write these lines to std. If the pattern contains punctuation or special characters, put them in single quotes so the shell will interpret the command properly. The 'cat' command combines data vertically and the 'paste' command combines data horizontally. Special characters need to be in quotes.