watchlogs 0.1.2

A simple, colourful logfile watcher

watchlogs

watchlogs is a simple python utility (requires >= 3.7) for watching multilpe log files and interleaving their output, in a manner that aims to achieve the functionality of tail -F, but with more colour.

Usage

watchlogs --log_files /path/to/log1.txt,/path/to/log2.txt,....

Installation

Installation can be handled via pip install watchlogs. However, if you prefer to hack around with the source code, it's only a single file.

Behaviour

watchlogs has the following behaviour when log.txt is updated (assuming that we have run watchlogs --log_files log.txt):

• action (appending): echo "x" >> log.txt
  outcome: x is printed to screen.

• action (moving/rotating): touch log2.txt ; echo "y" > log2.txt ; mv log2.txt log.txt
  outcome: y is printed to screen

• action (overwritng in-place): echo "z" > log.txt
  outcome: z is lost

Since I only use the first two actions while logging, this has sufficed for my needs, but the last behaviour is documented for completeness. It is likely possible to fix this, but it is not trivial to support with the current implementation and in practice it hasn't affected my use-case (watching slurm logs).

Implementation

watchlogs uses the pyinotify library to monitor OS events. In particular, it monitors for:

• IN_ATTRIB events to handle log rotation (or files being moved onto the current watches).
• IN_MODIFY events to detect when new text is added to the file.

The implementation was inspired by this StackOverflow comment.

Related projects

You may be interested in:

• pygtail - this also reads log files that have not been read (but as far as I am aware, only a single log file at a time.)