go build works fine but go run fails

Question

I have a few files in the main package under one directory:

main.go config.go server.go

When I do: "go build" the program builds perfect and runs fine. When I do: "go run main.go" it fails.

Output:

# command-line-arguments
./main.go:7: undefined: Config
./main.go:8: undefined: Server

The symbols that are undefined are structs and they are capitalised so should be exported.

My Go version: go1.1.2 linux/amd64

What is the `package` for `main.go` and `config.go` with `server.go`? If you are going to run them all three must have `package main`. — Kavu, Jan 22 '14 at 20:19
Keep in mind that `go run` is fairly limited. You should be using `go build` to build your package(s) and running it with ./packagename or packagename if it's on your PATH. — elithrar, Jan 22 '14 at 21:25
You can build and execute easily without go run: "go build && ./packagename" — Matthias, Jan 23 '14 at 11:12

score 58 · Accepted Answer · answered Jan 22 '14 at 20:33

58

This should work

go run main.go config.go server.go

Go run takes a file or files and it complies those and only those files which explains the missing symbols in the original post.

answered Jan 22 '14 at 20:33

Nick Craig-Wood

This indeed works but the wierd thing is that external imports (the ones you put in import()) do work perfectly without me having to specify them on the command line. – Roel Van Nyen Jan 22 '14 at 21:01
3

@RoelVanNyen That's not weird at all - since they're imported, the go toolchain knows where to look for them – Cubic Jan 22 '14 at 21:16
1

Would be great though if the companion packages were imported automatically by go run – Ian Lewis Feb 27 '14 at 16:31
1

@RoelVanNyen Why didn't you suggest `go run *.go`? – Gianfranco Reppucci Oct 17 '17 at 15:24
@RoelVanNyen This seems better -if has no side effects at all. All in all, why to write down each and every thing. – vahdet Dec 09 '17 at 10:46
1

There is a side effect for me: `$ go run *.go` `go run: cannot run *_test.go files (main_test.go)` There's a discussion around this [here](https://stackoverflow.com/questions/23695448/golang-run-all-go-files-within-current-directory-through-the-command-line-mul) – cody Aug 30 '18 at 13:50

score 33 · Answer 2 · answered Oct 09 '18 at 12:29

33

You could execute it as:

go run .

so you don't have to include all files manually.

answered Oct 09 '18 at 12:29

Daniel Pecos

score 1 · Answer 3 · answered May 06 '22 at 15:23

Good practise would be to create a package for it and run

go run ./app

Ex. Folder Structure

    ├──app/
    |  ├──main.go
    |  ├──config.go
    |  ├──server.go
    ├──bin/
    |  ├──foo.go
    └──pkg/
       └──bar.go

3 Answers3