lumberjack - A logging interface for shell scripts


Lumberjack is a logging interface for shell scripts.


Lumberjack handles your logs for you. When you set a logfile and log level, it is linked to the process ID of the script in which it is run, so that further calls need only contain the message to append to the logfile.



Although lumberjack can be used within any script, ZSH 5+ must be installed and in your $PATH in order to run it.


zulu install lumberjack


Simply move the lj executable to somewhere in your $PATH.

git clone
mv lumberjack/lj /usr/local/bin


Lumberjack should be called a first time to set the log file and level.

lj --file /usr/local/var/log/myawesomescript.log --level critical

Once done, further calls need only contain the level at which that log applies, and the message.

lj critical ‘Something went wrong’

The level is any one of emergency, alert, critical, error, warning, notice, info or debug. If the level is not set, the default is notice. Likewise, when logging you can omit the first parameter, and a level of notice is assumed.

lj 'This is a notice'

If a message is logged at a level lower than that which is set, it is gracefully ignored. This allows you to dynamically set the log level based on parameters passed to your script.

#!/usr/bin/env zsh

# Parse CLI options
zparseopts -D v=verbose -verbose=verbose

# Set the log level
local level=critical
[[ $verbose ]] && level=notice

# Initialise lumberjack
lj --file ~/log --level $level

lj 'This is a notice'

In the above example, running script.zsh would result in nothing being output to the log. Running script.zsh --verbose would increase the log level, allowing the notice to be appended to the log file.


  • Allow log format to be modified
  • Add additional drivers for send logs to services like Sentry etc.


Copyright (c) 2016 James Dinsdale [email protected] (

Lumberjack is licensed under The MIT License (MIT)


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Mar 3, 2022