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/
"

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 😄