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README.md

@@ -0,0 +1,69 @@
+# loadenv
+
+Loads environment files before running a command without polluting your environment
+
+## Source code
+
+You can find the source code here: [git.milar.in](https://git.milar.in/milarin/loadenv)
+
+## Installation
+
+If you have Go installed, you can simply go install the program: `go install git.milar.in/milarin/loadenv@latest`
+
+There are pre-compiled executables for various platforms on the [repository](https://git.milar.in/milarin/loadenv/releases).
+
+## License
+
+Distributed under the MIT License. See [LICENSE.md](https://git.milar.in/milarin/loadenv/src/branch/main/LICENSE.md)
+
+## Usage
+
+`loadenv` loads the environment file provided via `-f` into the environment and runs the command provided after the arguments.
+If no file is provided, `.env` is used by default.
+If no command is provided, `loadenv` prints all environment variables to stdout.
+
+---
+
+The variables will only be available to the given command. They will be deleted after the command exits.
+`loadenv` can be useful when working with programs which heavily use environment variables.
+
+```sh
+$ cat .env
+# production server configuration
+DATABASE_HOST=prod-server.com
+DATABASE_USER=milarin
+DATABASE_PASS=my-super-secure-password
+
+$ # show the 3 last added env variables
+$ loadenv | tail -n 3
+DATABASE_HOST=prod-server.com
+DATABASE_USER=milarin
+DATABASE_PASS=my-super-secure-password
+
+$ cat dev.env
+# development server configuration
+DATABASE_HOST=dev-server.com
+DATABASE_USER=milarin
+DATABASE_PASS=my-super-secure-password
+
+$ # load dev.env into environment and run the command env. show last 3 lines
+$ loadenv -f dev.env env | tail -n 3
+DATABASE_HOST=dev-server.com
+DATABASE_USER=milarin
+DATABASE_PASS=my-super-secure-password
+```
+
+environment variables in that file will be expanded:
+
+```sh
+$ env | grep USER # current value of $USER
+USER=milarin
+
+$ cat .env
+# expand $USER reference
+USERNAME=$USER
+
+$ loadenv | tail -n 1
+USERNAME=milarin
+```
+

go.mod

@@ -1,3 +1,5 @@
-module git.tordarus.net/Tordarus/loadenv
+module git.milar.in/milarin/loadenv
 
 go 1.18
+
+require git.milar.in/milarin/buildinfo v1.0.0

go.sum

@@ -0,0 +1,2 @@
+git.milar.in/milarin/buildinfo v1.0.0 h1:tw98GupUYl/0a/3aPGuezhE4wseycOSsbcLp70hy60U=
+git.milar.in/milarin/buildinfo v1.0.0/go.mod h1:arI9ZoENOgcZcanv25k9y4dKDUhPp0buJrlVerGruas=

main.go

@@ -8,6 +8,8 @@ import (
 	"os"
 	"os/exec"
 	"regexp"
+
+	"git.milar.in/milarin/buildinfo"
 )
 
 var (
@@ -15,31 +17,37 @@ var (
 
 	EnvVarRegex     = regexp.MustCompile(`^(.*?)=(.*?)$`)
 	EnvCommentRegex = regexp.MustCompile(`^[ \t]*#.*?$`)
+
+	ShowVersion = flag.Bool("v", false, "show version and exit")
 )
 
 func main() {
 	flag.Parse()
 
+	if *ShowVersion {
+		buildinfo.Print(buildinfo.Options{})
+		return
+	}
+
 	envFile, err := os.Open(*EnvFilePath)
 	if err != nil {
-		panic(err)
+		fmt.Fprintf(os.Stderr, "could not open file '%s': %s\n", *EnvFilePath, err.(*os.PathError).Err)
+		return
 	}
 	defer envFile.Close()
 
-	envVars := parseEnvFile(envFile)
+	parseEnvFile(envFile)
 	args := flag.Args()
 
-	newEnv := append(os.Environ(), envVars...)
-
 	if len(args) == 0 {
-		for _, envVar := range newEnv {
+		for _, envVar := range os.Environ() {
 			fmt.Println(envVar)
 		}
 		return
 	}
 
 	cmd := exec.Command(args[0], args[1:]...)
-	cmd.Env = newEnv
+	cmd.Env = os.Environ()
 
 	cmd.Stdin = os.Stdin
 	cmd.Stdout = os.Stdout
@@ -55,21 +63,19 @@ func main() {
 	}
 }
 
-func parseEnvFile(r io.Reader) []string {
+func parseEnvFile(r io.Reader) {
-	env := make([]string, 0)
 	s := bufio.NewScanner(r)
 	l := 0
+
 	for s.Scan() {
 		l++
 
 		matches := EnvVarRegex.FindStringSubmatch(s.Text())
 		if len(matches) != 0 {
 			key, value := matches[1], os.ExpandEnv(matches[2])
-			env = append(env, fmt.Sprintf("%s=%s", key, value))
+			os.Setenv(key, value)
-		} else if !EnvCommentRegex.MatchString(s.Text()) {
+		} else if s.Text() != "" && !EnvCommentRegex.MatchString(s.Text()) {
 			panic(fmt.Sprintf("invalid env syntax on line %d", l))
 		}
 	}
-
-	return env
 }