Added helper to find binaries in path or directory

which/which.go

@@ -0,0 +1,54 @@
+package which
+
+import (
+	"errors"
+	"os"
+	"path"
+	"strings"
+)
+
+// Common named errors to match in programs using this library
+var (
+	ErrBinaryNotFound    = errors.New("Requested binary was not found")
+	ErrNoSearchSpecified = errors.New("You need to specify a binary to search")
+)
+
+// FindInPath searches the specified binary in directories listed in $PATH and returns first match
+func FindInPath(binary string) (string, error) {
+	pathEnv := os.Getenv("PATH")
+	if len(pathEnv) == 0 {
+		return "", errors.New("Found empty $PATH, not able to search $PATH")
+	}
+
+	for _, part := range strings.Split(pathEnv, ":") {
+		if len(part) == 0 {
+			continue
+		}
+
+		if found, err := FindInDirectory(binary, part); err != nil {
+			return "", err
+		} else if found {
+			return path.Join(part, binary), nil
+		}
+	}
+
+	return "", ErrBinaryNotFound
+}
+
+// FindInDirectory checks whether the specified file is present in the directory
+func FindInDirectory(binary, directory string) (bool, error) {
+	if len(binary) == 0 {
+		return false, ErrNoSearchSpecified
+	}
+
+	_, err := os.Stat(path.Join(directory, binary))
+
+	switch {
+	case err == nil:
+		return true, nil
+	case os.IsNotExist(err):
+		return false, nil
+	default:
+		return false, err
+	}
+}

which/which_suite_test.go

@@ -0,0 +1,13 @@
+package which_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestWhich(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Which Suite")
+}

which/which_test.go

@@ -0,0 +1,63 @@
+package which_test
+
+import (
+	. "github.com/Luzifer/go_helpers/which"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Which", func() {
+	var (
+		result string
+		err    error
+		found  bool
+	)
+
+	Context("With a file available on linux systems", func() {
+		BeforeEach(func() {
+			found, err = FindInDirectory("bash", "/bin")
+		})
+
+		It("should not have errored", func() {
+			Expect(err).NotTo(HaveOccurred())
+		})
+		It("should have found the binary at /bin/bash", func() {
+			Expect(found).To(BeTrue())
+		})
+	})
+
+	Context("Searching bash on the system", func() {
+		BeforeEach(func() {
+			result, err = FindInPath("bash")
+		})
+
+		It("should not have errored", func() {
+			Expect(err).NotTo(HaveOccurred())
+		})
+		It("should have a result", func() {
+			Expect(len(result)).NotTo(Equal(0))
+		})
+	})
+
+	Context("Searching a non existent file", func() {
+		BeforeEach(func() {
+			result, err = FindInPath("dfqoiwurgtqi3uegrds")
+		})
+
+		It("should have errored", func() {
+			Expect(err).To(Equal(ErrBinaryNotFound))
+		})
+	})
+
+	Context("Searching an empty file", func() {
+		BeforeEach(func() {
+			result, err = FindInPath("")
+		})
+
+		It("should have errored", func() {
+			Expect(err).To(Equal(ErrNoSearchSpecified))
+		})
+	})
+
+})