$ cargo new rust_projects --bin
$ ls
Desktop Documents Downloads Music Pictures Public rust_projects Templates Videos
$ cd rust_projects/
$ ls
Cargo.toml src
$ cd src
$ ls
main.rs
$ geany main.rs
$ cd -
/home/ukse/rust_projects
$ pwd
/home/ukse/rust_projects
$ cargo build
There is no main file "executable" in all project folder.