Logwatch Error - Logwatch is a program that will parse your logs and send you an email every day about what has taken place on your server, a very friendly program. With Ubuntu I kept getting this error, though I checked, I could not find a solution so, as it looked like it was missing a location /var/cache/logwatch, I created one and it worked perfectly.

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...

There are times when you will want to trim some information from the output of a command. This may be because you want to feed that output into another command. Whatever the reason for wanting to manipulate the output, awk is one of many tools available in GNU/Linux to perform this task.

Last week we provided an introduction to the Linux system logs. (See Logs: Your Linux System’s Lovable Worker Bees.) Now, what will you, as a system administrator, use to watch logs? Logwatch, of course. As so many others have succinctly put it, messing with log files is a royal pain in the backside. Logwatch makes the experience of keeping track of system activity almost painless for you.

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.

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 [ | ].

iptstate  displays  information  held  in  the IP Tables state table in real-time in a top-like format.  Output can be sorted by any field,  or any field reversed.

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.

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.