Go build: “Cannot find package” (even though GOPAT

问题:

Even though I have GOPATH properly set, I still can't get "go build" or "go run" to find my own packages. What am I doing wrong? Thank you so much!

$ echo $GOROOT
/usr/local/go

$ echo $GOPATH
/home/mitchell/go

$ cat ~/main.go
package main
import "foobar"
func main() { }

$ cat /home/mitchell/go/src/foobar.go
package foobar

$ go build main.go
main.go:3:8: import "foobar": cannot find package

回答1:

It does not work because your foobar.go source file is not in a directory called foobar. go build and go install try to match directories, not source files.

1. Set $GOPATH to a valid directory, e.g. export GOPATH="$HOME/go"
2. Move foobar.go to $GOPATH/src/foobar/foobar.go and building should work just fine.

Additional recommended steps:

1. Add $GOPATH/bin to your $PATH by: PATH="$GOPATH/bin:$PATH"
2. Move main.go to a subfolder of $GOPATH/src, e.g. $GOPATH/src/test
3. go install test should now create an executable in $GOPATH/bin that can be called by typing test into your terminal.

回答2:

Edit: since you meant GOPATH, see fasmat's answer (upvoted)

As mentioned in "How do I make go find my package?", you need to put a package xxx in a directory xxx.

See the Go language spec:

package math

A set of files sharing the same PackageName form the implementation of a package.
An implementation may require that all source files for a package inhabit the same directory.

The Code organization mentions:

When building a program that imports the package "widget" the go command looks for src/pkg/widget inside the Go root, and then—if the package source isn't found there—it searches for src/widget inside each workspace in order.

(a "workspace" is a path entry in your GOPATH: that variable can reference multiple paths for your 'src, bin, pkg' to be)

---

(Original answer)

You also should set GOPATH to ~/go, not GOROOT, as illustrated in "How to Write Go Code".

The Go path is used to resolve import statements. It is implemented by and documented in the go/build package.

The GOPATH environment variable lists places to look for Go code.
On Unix, the value is a colon-separated string.
On Windows, the value is a semicolon-separated string.
On Plan 9, the value is a list.

That is different from GOROOT:

The Go binary distributions assume they will be installed in /usr/local/go (or c:\Go under Windows), but it is possible to install them in a different location.
If you do this, you will need to set the GOROOT environment variable to that directory when using the Go tools.

回答3:

TL;DR: Follow Go conventions! (lesson learned the hard way), check for old go versions and remove them. Install latest.

For me the solution was different. I worked on a shared Linux server and after verifying my GOPATH and other environment variables several times it still didn't work. I encountered several errors including 'Cannot find package' and 'unrecognized import path'. After trying to reinstall with this solution by the instructions on golang.org (including the uninstall part) still encountered problems.

Took me some time to realize that there's still an old version that hasn't been uninstalled (running go version then which go again... DAHH) which got me to this question and finally solved.

回答4:

Have you tried adding the absolute directory of go to your 'path'?

export PATH=$PATH:/directory/to/go/