ENV.shift

ENV.shift → [name, value] or nil

static VALUE
env_shift(VALUE _)
{
    VALUE result = Qnil;
    VALUE key = Qnil;

    ENV_LOCK();
    {
        char **env = GET_ENVIRON(environ);
        if (*env) {
            const char *p = *env;
            char *s = strchr(p, '=');
            if (s) {
                key = env_str_new(p, s-p);
                VALUE val = env_str_new2(getenv(RSTRING_PTR(key)));
                result = rb_assoc_new(key, val);
            }
        }
        FREE_ENVIRON(environ);
    }
    ENV_UNLOCK();

    if (!NIL_P(key)) {
        env_delete(key);
    }

    return result;
}

Removes the first environment variable from ENV and returns a 2-element Array containing its name and value:

Example

ENV.replace('foo' => '0', 'bar' => '1')
ENV.to_hash # => {'bar' => '1', 'foo' => '0'}
ENV.shift # => ['bar', '1']
ENV.to_hash # => {'foo' => '0'}

Exactly which environment variable is “first” is OS-dependent. See About Ordering.

Returns nil if the environment is empty.

See also .select! .size .select .slice also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0

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