Implement running commands

common.go

@@ -0,0 +1,18 @@
+package coreutils
+
+import (
+	"fmt"
+	"os"
+)
+
+// PrintStrings prints each string in strings on a new line
+func PrintStrings(strings []string) {
+	for _, str := range strings {
+		fmt.Println(str)
+	}
+}
+
+// PrintEnv prints all environment variables
+func PrintEnv() {
+	PrintStrings(os.Environ())
+}

env/env.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"os"
+	"os/exec"
+
+	"gopkg.in/alecthomas/kingpin.v2"
+	common "source.heropunch.io/tomo/go-coreutils"
+)
+
+func main() {
+	app := kingpin.New("env", "modify the environment, then print it or run a command")
+	ignoreEnv := kingpin.Flag(
+		"ignore-environment",
+		"Completely ignore the existing environment and execute cmd only with each (var, value) tuple specified.",
+	).Short('i').Bool()
+	unset := kingpin.Flag("unset", "Unset var in the environment.").PlaceHolder("var").Short('u').Strings()
+
+	cmd := kingpin.Arg("cmd", "").String()
+	args := kingpin.Arg("args", "").Strings()
+
+	kingpin.Parse()
+
+	for _, key := range *unset {
+		os.Unsetenv(key)
+	}
+
+	if *ignoreEnv {
+		os.Clearenv()
+	}
+
+	if *cmd == "" {
+		common.PrintEnv()
+		os.Exit(0)
+	}
+	command := exec.Command(*cmd, *args...)
+	err := command.Run()
+	app.FatalIfError(err, "error running command:")
+}

error.go

@@ -1,4 +1,4 @@
-package common
+package coreutils
 
 import (
 	"fmt"

go.mod

@@ -1,6 +1,9 @@
 module source.heropunch.io/tomo/go-coreutils
 
 require (
+	github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc // indirect
+	github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf // indirect
 	github.com/alexflint/go-arg v1.0.0
 	github.com/stretchr/testify v1.3.0
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 )

go.sum

@@ -1,9 +1,14 @@
+github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc h1:cAKDfWh5VpdgMhJosfJnn5/FoN2SRZ4p7fJNX58YPaU=
+github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf h1:qet1QNfXsQxTZqLG4oE62mJzwPIB8+Tee4RNCL9ulrY=
+github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alexflint/go-arg v1.0.0 h1:VWNnY3DyBHiq5lcwY2FlCE5t5qyHNV0o5i1bkCIHprU=
 github.com/alexflint/go-arg v1.0.0/go.mod h1:Cto8k5VtkP4pp0EXiWD4ZJMFOOinZ38ggVcQ/6CGuRI=
 github.com/alexflint/go-scalar v1.0.0 h1:NGupf1XV/Xb04wXskDFzS0KWOLH632W/EO4fAFi+A70=
 github.com/alexflint/go-scalar v1.0.0/go.mod h1:GpHzbCOZXEKMEcygYQ5n/aa4Aq84zbxjy3MxYW0gjYw=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -14,3 +19,5 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=

printenv/printenv.go

@@ -1,19 +1,13 @@
 package main
 
 import (
-	"fmt"
 	"os"
+	common "source.heropunch.io/tomo/go-coreutils"
 )
 
-func printStrings(strings []string) {
-	for _, str := range strings {
-		fmt.Println(str)
-	}
-}
-
 func main() {
 	if len(os.Args) == 1 {
-		printStrings(os.Environ())
+		common.PrintEnv()
 		os.Exit(0)
 	}
 
@@ -27,6 +21,6 @@ func main() {
 			exitCode = 1
 		}
 	}
-	printStrings(envVars)
+	common.PrintStrings(envVars)
 	os.Exit(exitCode)
 }