$ cargo run -- '*' src/main.rs ; echo "Status code: $?"

    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg '*' src/main.rs`
regex parse error:
    *
    ^
error: repetition operator missing expression
Status code: 2

$ cargo run -- 'main' src/main.rs ; echo "Status code: $?"

    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg main src/main.rs`
56:fn main() {
Status code: 0

cargo run -- 'this_does_not_match' src/main.rs ; echo "Status code: $?"


    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/rg this_does_not_match src/main.rs`
Status code: 1