Further Configurations

loggit2 can be used immediately and fully without configuration after installation. However, to fully utilize the potential of loggit2, some configurations can be made.

Configuration System

loggit2 uses a three-tier configuration system:

  1. Meta/System-wide Configuration
  2. Global/Session-wide1 Configuration
  3. Local/Function-specific Configuration

The first tier is the Meta or System-wide Configuration. It is defined by environment variables that are read by loggit2 when the package is loaded. These settings then serve as default values for the session-wide configuration.

The second tier is the Global or Session-wide Configuration. It is defined by the set_*() functions of loggit2.

The third tier is the Local or Function-specific Configuration, implemented through the arguments of the functions. For a quick overview of the functions, refer to the Getting Started Vignette.

Each time a function of loggit2 is called, the settings from the three tiers are combined. A higher tier/specificity configuration always takes precedence over a lower tier/specificity configuration.

Configuration Options

The configuration options of loggit2 are described below. For details, refer to the function documentation.

Log file

The log file can be set either via the environment variable FILE_LOGGIT2, the function set_log_file(), or the logfile argument of the logging functions loggit() and with_loggit(). The wrappers of the base R condition handler always use the session-wide configuration.

old_log <- loggit2::set_logfile(logfile = "logfile.log")
#> Log file set to C:/Users/a501562/AppData/Local/Temp/RtmpyKvflv/logfile.log
loggit2::loggit(
  log_lvl = "DEBUG",
  log_msg = "This message will be logged to `logfile.log`."
)
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "DEBUG", "log_msg": "This message will be logged to `logfile.log`."}


loggit2::loggit(
  log_lvl = "DEBUG",
  log_msg = "This message will be logged to `otherlogfile.log`.",
  logfile = "otherlogfile.log"
)
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "DEBUG", "log_msg": "This message will be logged to `otherlogfile.log`."}


loggit2::with_loggit(logfile = "logfile2.log", {
  base::message("This message will be logged to `logfile2.log`.")
})
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged to `logfile2.log`.\n"}
#> This message will be logged to `logfile2.log`.

loggit2::set_logfile(old_log)
#> Log file set to C:/Users/a501562/AppData/Local/Temp/RtmpyKvflv/loggit.log

Log level

The log level can be set either via the environment variable LEVEL_LOGGIT2 or the function set_log_level(). The .loggit argument can also be passed to the wrappers of the base R condition handler to enforce logging (TRUE) or suppress it (FALSE). The logging function loggit() can enforce logging through the ignore_log_level argument. with_loggit() allows setting a log level for the code block being executed.

old_log_lvl <- loggit2::set_log_level("INFO")
#> Log level set to 3 (INFO)
loggit2::message("This message will be logged, since the log level is INFO.")
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged, since the log level is INFO.\n"}
#> This message will be logged, since the log level is INFO.
loggit2::loggit(
  log_lvl = "DEBUG",
  log_msg = "This message will not be logged, since the log level is INFO."
)
loggit2::loggit(
  log_lvl = "DEBUG", "This message will be logged because the log level is ignored.",
  ignore_log_level = TRUE
)
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "DEBUG", "log_msg": "This message will be logged because the log level is ignored."}
loggit2::warning(
  "This warning message will not be logged, since .loggit = FALSE.",
  .loggit = FALSE
)
#> Warning: This warning message will not be logged, since .loggit = FALSE.

loggit2::set_log_level("ERROR")
#> Log level set to 1 (ERROR)
loggit2::warning("This warning will not be logged, since the log level is set to ERROR.")
#> Warning: This warning will not be logged, since the log level is set to ERROR.
loggit2::message("This message will be logged, since .loggit = TRUE.", .loggit = TRUE)
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged, since .loggit = TRUE.\n"}
#> This message will be logged, since .loggit = TRUE.
loggit2::stop("This error message will be logged because the log level is set to ERROR.")
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "ERROR", "log_msg": "This error message will be logged because the log level is set to ERROR."}
#> Error: This error message will be logged because the log level is set to ERROR.

loggit2::with_loggit(log_level = "DEBUG", {
  base::message("This message will be logged because the log level is set to DEBUG.")
})
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged because the log level is set to DEBUG.\n"}
#> This message will be logged because the log level is set to DEBUG.

loggit2::set_log_level(old_log_lvl)
#> Log level set to 4 (DEBUG)

Echo

Whether log messages should also be output to stdout can be controlled via the environment variable ECHO_LOGGIT2 or the function set_echo(). Additionally, all logging functions and wrappers of the base R condition handler allow direct control via the echo argument.

old_echo <- loggit2::set_echo(FALSE)
#> Echo set to FALSE
loggit2::message("This message will not be logged, but it will be output to the console.")
#> This message will not be logged, but it will be output to the console.
loggit2::message("This message will be logged and output to the console.", echo = TRUE)
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged and output to the console.\n"}
#> This message will be logged and output to the console.

loggit2::set_echo(TRUE, confirm = FALSE)
loggit2::message("This message will be logged and output to the console.")
#> {"timestamp": "2025-06-01T20:18:49+0200", "log_lvl": "INFO", "log_msg": "This message will be logged and output to the console.\n"}
#> This message will be logged and output to the console.
loggit2::message("This message will be logged, but it will not be echoed.", echo = FALSE)
#> This message will be logged, but it will not be echoed.

loggit2::with_loggit(echo = FALSE, {
  base::message("This message will be logged, but it will not be output to the console.")
})
#> This message will be logged, but it will not be output to the console.

loggit2::set_echo(old_echo)
#> Echo set to TRUE

Timestamp format

The format of the timestamp can be controlled via the environment variable TIMESTAMP_LOGGIT2 or the function set_timestamp_format().

old_ts <- loggit2::set_timestamp_format("%H:%M:%S")
#> Timestamp format set to %H:%M:%S.
#> Current time in this format: 20:18:49
loggit2::message("This message will be logged with a timestamp in the format HH:MM:SS.")
#> {"timestamp": "20:18:49", "log_lvl": "INFO", "log_msg": "This message will be logged with a timestamp in the format HH:MM:SS.\n"}
#> This message will be logged with a timestamp in the format HH:MM:SS.

loggit2::set_timestamp_format(old_ts)
#> Timestamp format set to %Y-%m-%dT%H:%M:%S%z.
#> Current time in this format: 2025-06-01T20:18:49+0200

Temporary Configuration

Depending on the use case, it may be useful to change temporary configurations, e.g., to log to a different file in a specific code block or to log a particular part of the code with more details (higher log level).

One way is to manually set and reset the configurations (e.g., by using on.exit()), but this is cumbersome and error-prone.

An alternative is to use with_loggit(). As mentioned above, almost all configurations can be adjusted directly in with_loggit().

  1. Note: “Session-wide” means that (unless locally configured otherwise) calls to loggit2 functions in other packages will use the same settings. Consider this when using loggit2 in a package that will be used elsewhere.↩︎