Default behavious changed: Filenames that look like hashes are skipped. Pass --always to override this.

Fortune for lazy-rebuild's current commit: Future small blessing − 末小吉

Makefile

@@ -1,5 +1,7 @@
 
-all: clean lazy-rebuild test
+.PHONY: all
+all: | clean 
+	$(MAKE) lazy-rebuild test
 
 clean:
 	rm -rf test

go.mod

@@ -0,0 +1,3 @@
+module lazy-rebuild
+
+go 1.17

lazy-rebuild.go

@@ -1,4 +1,3 @@
-//go:binary-only-package
 package main
 
 import (
@@ -12,6 +11,7 @@ import (
 	"os"
 	"sync"
 	"strconv"
+	"regexp"
 )
 
 var keepLongExt bool = false
@@ -42,6 +42,12 @@ func hash(file string) []byte {
 	return h.Sum(nil)
 }
 
+var isHashRE *regexp.Regexp = regexp.MustCompile("^[0-9a-f]{64}$")
+func is_hash(name string) bool {
+	name = strings.Split(name, ".")[0]
+	return isHashRE.MatchString(name)
+}
+
 func extractExt(x string) string {
 	if (keepLongExt) {
 		return last(strings.SplitN(x, ".", 2)[1:])
@@ -50,8 +56,13 @@ func extractExt(x string) string {
 	}
 }
 
+var alwaysCheck bool = false
 func dofile(i int, y string) {
 	loc, x := filepath.Split(y)
+	if !alwaysCheck && is_hash(x) {
+		fmt.Printf("E: %s already a hash, skipping.\n", x)
+		return
+	}
 	sha := hash(y)
 	str := fmt.Sprintf("%x", sha)
 	newname := fmt.Sprintf("%s%s%s", loc, str, extractExt(x))
@@ -72,7 +83,7 @@ func main() {
 	var wg sync.WaitGroup
 	
 	if (len(ar) < 1) {
-		fmt.Printf("Usage: %s [--long] [--fake] [--recurse] [-quiet] [--threads <number>] <file ...>\n\t--long\tKeep long file extensions\n\t--fake\tDo not rename files.\n\t--recurse\tWalk path recursively.\n\t--quiet\tDo not show (some) errors.\n", os.Args[0])
+		fmt.Printf("Usage: %s [--long] [--fake] [--recurse] [-quiet] [--threads <number>] [--always] <file ...>\n\t--long\tKeep long file extensions\n\t--fake\tDo not rename files.\n\t--recurse\tWalk path recursively.\n\t--quiet\tDo not show (some) errors.\n\t--always\tDo not skip filenames which are already hashes.\n", os.Args[0])
 		return;
 	}
 	var ignore = false
@@ -91,6 +102,8 @@ func main() {
 				recurse = !recurse
 			case "quiet":
 				noErr = !noErr
+			case "always":
+				alwaysCheck = true
 			case "threads":
 				if i<len(ar)-1 {
 					if th, err := strconv.Atoi(ar[i+1]); err ==nil {