clog: Custom color for logs

I seem to be awash of colorizing programs as I chip away at the C section. This is clog, which the home page describes as a colorized log tail utility.


That’s mostly true. It does colorize text and it does apply more to logs than straight text files. It lacks a feature or two that would make it a peer of tail.

Mostly, it lacks the ability to strain out the last lines of a log. By default, clog dumps everything to STDOUT, and ignores flags like -10 that are native to tail. A bit of a misnomer, then.

You have two options in your .clogrc file: either highlight an entire line, or highlight matching sequences of letters. (You can also suppress lines, which might be useful.) In that way you could use clog as a kind of stylized grep, and add a few more color options.

Some shortcomings: When you highlight a string of letters or a word, you will only see highlighting on the first occurrence. As far as I could tell, there was no way to highlight the same sequence multiple times in the same line. Several different colors on the same line will work, but only the first match for each color.

Furthermore, if you ask for full-line highlighting and the line matches more than one filter, you’ll only see one highlighting. I couldn’t make clog split highlighting. You can, however, highlight letter sequences overtop of line highlighting.

Those are shortcomings, but only if you’re trying to make clog behave like a strict color filter, and not a log colorizer. Think of clog like ccze, not like colout (or highlighter or pygments).

On the plus side, clog’s syntax for screening colors is terrifically simple. Step through the first three or four examples and you’ll have multicolor log displays in no time. And clog supplies date and time functions in case you want to stamp the output with either of those.

clog is a good tool, but not one I plan on adopting. I rarely peek at my logs anyway, and clog doesn’t handle enough grep-like colorizing to take over that role. If its abilities expand, I might consider it.