log4j logs in color!

log-color

#!/bin/bash -eu
#
# Color log4j-style logs for easier visual parsing.
#
# Usage:
#   tail foo.log | log-color
#   run-service | log-color

black="`   tput setaf 0; tput bold`"
red="`     tput setaf 1; tput bold`"
green="`   tput setaf 2; tput bold`"
yellow="`  tput setaf 3; tput bold`"
blue="`    tput setaf 4; tput bold`"
magenta="` tput setaf 5; tput bold`"
cyan="`    tput setaf 6; tput bold`"
white="`   tput setaf 7; tput bold`"
#off="`     tput sgr0`"
off="`     echo -ne "\x0f"`" # (Works better on both osx and linux...)

exec sed -r "

  # Timestamps
  s/^\[[0-9]{4}[^]]*\]/$black\\0$off/
  s/^[0-9]{4}-[0-9:,/ -]*/$black\\0$off/

  # Log levels
  s/\\b(FATAL|CRITICAL)\\b/$magenta\\0$off/g
  s/\\bERROR\\b/$red\\0$off/g
  s/\\bWARN(ING)?\\b/$yellow\\0$off/g
  s/\\bINFO\\b/$green\\0$off/g
  s/\\bDEBUG\\b/$blue\\0$off/g
  s/\\bTRACE\\b/$cyan\\0$off/g

  # Grouped things
  s/ \[[^]]+\] \S+ - /$black\\0$off/
  s/ \([a-zA-Z_][a-zA-Z0-9_$.:]*\)$/$black\\0$off/
"

I wanted to give your script a try, but I get a "sed: illegal option --r " exception on Mac OS. May you provide a version without the "- r" parameter? This would be very helpful. Your scrips seems to be the most promising as I have seen so far.

Hi jdanbrown, thank you for sharing this script with us. It's short while very powerful.

And hello chilladelia. For the mac, you may install home brew first, then install gun-sed to replace the mac original sed.
Use command below:
brew install gnu-sed --with-default-names
After that, the log-color script can be used in mac os.

And for simplicity. I write a very simple script to easily use to monitor the input into a log4j log file.
Save the below code into a file e.g. sslog:

#! /bin/sh

echo $1 | xargs tail -f | log-color

Then copy both sslog and log-color into /usr/local/bin. Give both of them execute privileges:

chmod +x /usr/local/bin/sslog
chmod +x /usr/local/bin/log-color

Finally, you can monitor a log4j log file from everywhere by type the following command:
slog log4j.log

Have fun!

Thanks a lot, works like a charm, even piped behind a tail -f through a kubectl exec 😄