Environment variable helper

main.go

// Build this using `go build` and put it in your PATH

package main

import (
	"encoding/json"
	"os"
	"os/exec"
	"strings"
)

func main() {
	f, err := os.Open(os.Getenv("HOME") + "/.erc")
	if err != nil {
		println(`Couldn't open ~/.erc, please create that file.
    
    Example format:
    { "/Users/me/Projects/aws/": ["AWS_ACCESS_KEY_ID=asd","AWS_SECRET_ACCESS_KEY=sdf"] }
    `)
		return
	}
	defer f.Close()
	vars := map[string][]string{}
	err = json.NewDecoder(f).Decode(&vars)
	if err != nil {
		println(`~/.erc was in an invalid format: ` + err.Error() + `.
    
    Example format:
    { "/Users/me/Projects/aws/": ["AWS_ACCESS_KEY_ID=asd","AWS_SECRET_ACCESS_KEY=sdf"] }
    `)
		return
	}
	wd, _ := os.Getwd()
	env := os.Environ()
	for pathPrefix, envs := range vars {
		if strings.HasPrefix(wd, pathPrefix) {
			env = append(env, envs...)
		}
	}
	cmd := exec.Command("sh", "-c", strings.Join(os.Args[1:], " "))
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Env = env
	err = cmd.Run()
	if err != nil {
		os.Exit(1)
	}
}

To pass down arguments with spaces in them, you need to double escape them, e.g.

cat 'a b' => cat 'a\ b'
cat a\ b => cat a\\ b