We have already seen in Chapter 11, Summarizing Logs with Awk, how we can create complex reports from large amounts of data mined from purely text files. Similarly, we can create extensive reports using the output from standard command-line tools, such as the lastlog tool. In itself lastlog can report the last login time for all users. Often though, we may wish to filter the output from lastlog. Perhaps you need to exclude the user accounts that have never been used to login to the system. It may also be irrelevant to report on root, as the account may be predominately used for sudo only and not used to record regularly for standard logins.

In working through this chapter, we will work both with lastlog and formatting of XML data. As this is the last chapter in which we investigate awk, we will configure record separators. We have already seen the use of field separators in awk but we can change the default record separator from a newline to something...