The output of most GNU command line tools is normally sent to the terminal (ie – standard output). There are times when you would like to have the output saved as a file. Now, you could copy the text from the terminal and paste it into a text editor and save it, but there’s a better way...

One of the most powerful features of the Linux command line interface, (and other shells that conform to the POSIX standard) is the ability to pipeline output from one command as the input to another. This is done using the vertical bar or pipe character [ | ].

The Linux tee command is a way to write the standard output to a file. This is a little different from redirecting output to a file. In this case, the output is still send to standard out, but an additional copy is sent to create your text file.

I've shown previously how to use the more command to view text output. Today I'll show how to do the same thing with the less command. You can run the command simply by opening a terminal window and entering...

Logwatch is a modular log analyser that runs every night and mails you the results. It can also be run from command line.The output is by service and you can limit the output to one particular service. The subscripts which are responsible for the output, mostly convert the raw log lines in structured format.

You can copy command line output to X Windows clipboard directly using xclip command. You can read from standard input (keyboard), or from one or more files, and makes the data available as an X selection for pasting into any X applications such as gedit, OpenOffice or Firefox / email client.

A shell is a command interpreter which allows the user to interact with the computer. The way things work is simple: the user types in commands, the shell interprets them and performs the tasks it was asked to do, and finally it sends the result to the standard output (which is usually the screen). For example, the output of the ls command can be something like:

colordiff is a wrapper for diff and produces the same output as diff but with coloured syntax highlighting at the command line to improve readability. The output is similar to how a diff-generated patch might appear in Vim or Emacs with the appropriate syntax highlighting options enabled.

Command substitution takes the output of one Linux command and makes it an argument in another command.