var in std::env - Rust
Description: Fetches the environment variable `key` from the current process.

## var

# Function var

1.0.0 · Source

    pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError>

Expand description

Fetches the environment variable `key` from the current process.

## §Errors

Returns `VarError::NotPresent` if:

- The variable is not set.
- The variable’s name contains an equal sign or NUL (`'='` or `'\0'`).

Returns `VarError::NotUnicode` if the variable’s value is not valid Unicode. If this is not desired, consider using `var_os`.

Use `env!` or `option_env!` instead if you want to check environment variables at compile time.

## §Examples

    use std::env;

    let key = "HOME";
    match env::var(key) {
        Ok(val) => println!("{key}: {val:?}"),
        Err(e) => println!("couldn't interpret {key}: {e}"),
    }