Module env_logger

A simple logger that can be configured via environment variables.

• Crate ::env_logger.
• docs.rs
• crates.io
• GitHub

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env_logger is a logging implementation for the log facade that filters log messages based on environment variables. It’s the most commonly used logging backend in the Rust ecosystem, particularly for command-line applications.

By default, env_logger reads the RUST_LOG environment variable to determine which log messages to display. The format is target=level, where target can be a module path and level is one of error, warn, info, debug, or trace.

Examples

Initialize the logger at the start of your program:

use log::info;

fn main() {
    env_logger::init();

    info!("Starting application");
}

Modules

fmt

Formatting for log records.

Structs

Builder

Builder acts as builder for initializing a Logger.

Env

Set of environment variables to configure from.

Logger

The env logger.

Enums

Target

Log target, either stdout, stderr or a custom pipe.

TimestampPrecision

Formatting precision of timestamps.

WriteStyle

Whether or not to print styles to the target.

Constants

DEFAULT_FILTER_ENV

The default name for the environment variable to read filters from.

DEFAULT_WRITE_STYLE_ENV

The default name for the environment variable to read style preferences from.

Functions

builder

Create a new builder with the default environment variables.

from_envDeprecated

Create a builder from the given environment variables.

init

Initializes the global logger with an env logger.

init_from_env

Initializes the global logger with an env logger from the given environment variables.

try_init

Attempts to initialize the global logger with an env logger.

try_init_from_env

Attempts to initialize the global logger with an env logger from the given environment variables.