sha512sum now working

sha512sum/.gitignore

@@ -0,0 +1,2 @@
+sha512sum
+sha512sum.exe

sha512sum/Makefile

@@ -0,0 +1,4 @@
+
+
+build:
+	go build .

sha512sum/go.mod

@@ -0,0 +1,3 @@
+module lcthw.dev/go/go-coreutils/sha512sum
+
+go 1.25.3

sha512sum/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"flag"
+	"os"
+	"log"
+	"crypto/sha512"
+)
+
+type Opts struct {
+	Inputs []string
+}
+
+func parse_opts() Opts {
+	var opts Opts
+
+	flag.Parse()
+	opts.Inputs = flag.Args()
+
+	return opts
+}
+
+func to_hex(hash [sha512.Size]byte) string {
+	result := ""
+
+	for _, b := range hash {
+		result += fmt.Sprintf("%x", b)
+	}
+
+	return result
+}
+
+func main() {
+	opts := parse_opts()
+
+	for _, fname := range opts.Inputs {
+		in_data, err := os.ReadFile(fname)
+		if err != nil { log.Fatal(err) }
+
+		hash := sha512.Sum512(in_data)
+
+		fmt.Println(to_hex(hash), fname)
+	}
+}