err

Err is a word with both general and technical meanings. In English, it is the verb meaning to make a mistake or to be mistaken. The phrase to err is human is a long-standing expression highlighting human fallibility. Etymologically, err comes from Latin errare, meaning to wander or roam, and it has influenced modern usage in a range of contexts from casual speech to formal writing.

In computing, err is commonly used as an abbreviation for error. It appears in error messages, logs, and source code as a short form for "error." In many programming languages, err (or Err) is used as a variable or identifier that carries information about an error condition. This convention is especially visible in error-first callback patterns in JavaScript, where a function signature often begins with (err, result), and in other languages as a standard way to propagate failures.

Language-specific conventions often capitalize or differentiate the form. In Go, for example, functions frequently return a value and an error, with the error assigned to a variable commonly named err. In Bash, the shell can trap the ERR signal to run a handler when a command exits with a non-zero status. In languages such as Rust, the Err variant of a Result type represents a failure, guiding explicit error handling.

Overall, err serves as both a general term for mistakes and a tech shorthand used widely in software development to denote, propagate, and manage error conditions.