next, last : glob and regexp

next/last.go

@@ -1,14 +1,39 @@
 package next
 
 import (
+	"errors"
 	"fmt"
 	"os/exec"
+	"regexp"
+	"strings"
 )
 
-func Last() {
-	ls, err := exec.Command("ls").Output()
+const (
+	LS_CMD       = `ls -r [0-9]*.md`
+	LS_GREP_PIPE = `ls -r | grep -E '^[[:digit:]].*\.md'`
+	FILE_REGEXP  = `(?m)^([0-9]+)\.([[:alpha:]]*)\.*md$`
+)
+
+var fileRegexp *regexp.Regexp = regexp.MustCompile(FILE_REGEXP)
+
+func last() (string, error) {
+	// NOTE: globbing requires invoking the shell as cmd:
+	cmd := exec.Command("sh", "-c", LS_CMD)
+	ls, err := cmd.Output()
 	if err != nil {
-		fmt.Print(err)
+		return "", err
 	}
-	fmt.Printf("ls\n%s\n", string(ls))
+	lines := strings.Split(string(ls), "\n")
+	if len(lines) == 0 {
+		return "", errors.New("no um files in current dir")
+	}
+	return lines[0], nil
+}
+
+func Last() {
+	s, err := last()
+	if err != nil {
+		fmt.Printf("err: %v\n", err)
+	}
+	fmt.Println(s)
 }