Log Messages
| Recipe | Crates | Categories |
|---|---|---|
| Log a Debug Message to the Console |   |  |
| Log an Error Message to the Console | | |
Log to stdout Instead of stderr | | |
| Log Messages with a Custom Logger | | |
| Log to the Unix Syslog |  | |
Log a Debug Message to the Console
The log⮳ crate provides logging utilities. The env_logger⮳ crate configures logging via an environment variable. The log::debug⮳ macro works like other std::fmt⮳ formatted strings.
No output prints when running this code. By default, the log level is error⮳, and any lower levels are dropped.
Set the RUST_LOG⮳ environment variable to print the message:
RUST_LOG=debug cargo run
Cargo prints debugging information then the following line at the very end of the output:
DEBUG:main: Executing query: DROP TABLE students
Log an Error Message to the Console
Proper error handling considers exceptions exceptional. Here, an error logs to stderr with log's convenience macro log::error⮳.
Log to stdout Instead of stderr
log⮳
Creates a custom logger configuration using the env_logger::Builder::target⮳ to set the target of the log output to env_logger::fmt::Target⮳.
Log Messages with a Custom Logger
Implements a custom logger ConsoleLogger which prints to stdout. In order to use the logging macros, ConsoleLogger implements the log::Log⮳ trait and log::Log⮳ installs it.
Log to the Unix Syslog
log⮳
Logs messages to UNIX syslog⮳. Initializes logger backend with syslog::init⮳ syslog::init⮳ records the program submitting the log entry's classification, syslog::init⮳ denotes allowed log verbosity and Option<&str> holds optional application name.