clog - a colorized log tail utility

NOTE this is a fork of the excellent original work hosted at tasktools.org.

original text follows.

What is Clog?

Ever done something like this:

	$ tail -f /var/log/something.log

and left that running in a terminal, while you debug or run some program? Were you able to spot important information as it scrolled by? It's not easy.

Clog is a filter, that you run like this:

	$ tail -f /var/log/something.log | clog something

Clog Rules

The 'something' argument to clog is a section, which refers to a section in ~/.clogrc with a distinct set of rules. Those rules list patterns to look for, and actions to take when the pattern is matched by a line. A typical example might be that you want to highlight any line that contains the pattern 'severe'. This entry in ~/clogrc achieves this:

	something rule /severe/ --> bold line

This rule is in the 'something' section, the pattern is 'severe', and the action taken is to embolden the whole line. Pattern 'severe' should probably be more restrictive, because it will also match words like 'persevered', but that is optional.

Any color can be used, in both the 16- and 256-color space. Some examples are:

• bold
• underline
• bold blue
• underline on green
• black on white
• bold red on bright white
• rgb200 on grey4

Instead of coloring the whole line, specifying 'match' instead will only color the parts of the line that match.

The format of the rules is:

  <section> rule /<pattern>/ --> <color> <action>

The section is simply a way to allow multiple rules sets, so that one .clogrc file can serve multiple uses. The pattern is any supported Standard C Library regular expression. Action must be one of 'line', 'match', 'suppress' or 'blank'.

Note that there is a default section, called 'default'. Putting rules in the default section means that no section need be specified on the command line. Multiple sections may be specified, and the rules are combined.