log

The log package writes leveled log messages to stderr, and optionally to a file as well. Messages below the current level are dropped.

log::info("service starting")
log::debug("hidden: the default level is INFO")

log::set_level("DEBUG")
log::debug("now visible")
log::warn("disk usage above 80%")
log::error("could not reach database")

[INFO] [3/22/2026 6:00:00 PM] service starting
[DEBUG] [3/22/2026 6:00:00 PM] now visible
[WARN] [3/22/2026 6:00:00 PM] disk usage above 80%
[ERROR] [3/22/2026 6:00:00 PM] could not reach database

Levels

From least to most severe: DEBUG, INFO, WARN, ERROR, FATAL. set_level shows messages at that level and above; the default is INFO.

log::fatal(message) logs the message and then ends the program with exit code 1.

Options

log::set_file("/var/log/myapp.log")   # also append every message to this file
log::timestamps(false)                # drop the timestamp: "[INFO] message"

Functions

log::set_level

log::set_level(lv)

Sets the minimum log level. Messages below this level are suppressed.

Parameter	Type	Default	Description
lv	any

log::set_file

log::set_file(path)

Sets a file path to append log output to.

Parameter	Type	Default	Description
path	string		File path, or null to disable file output.

log::timestamps

log::timestamps(enabled)

Enables or disables timestamps in log output.

Parameter	Type	Default	Description
enabled	boolean		Whether to include timestamps.

log::debug

log::debug(msg)

Logs a DEBUG message.

Parameter	Type	Default	Description
msg	any		The message to log.

log::info

log::info(msg)

Logs an INFO message.

Parameter	Type	Default	Description
msg	any		The message to log.

log::warn

log::warn(msg)

Logs a WARN message.

Parameter	Type	Default	Description
msg	any		The message to log.

log::error

log::error(msg)

Logs an ERROR message.

Parameter	Type	Default	Description
msg	any		The message to log.

log::fatal

log::fatal(msg)

Logs a FATAL message and exits with code 1.

Parameter	Type	Default	Description
msg	any		The message to log.