Add the two options netbsd has for this command.

tests/factor.test

@@ -20,3 +20,8 @@ testing "10000000019" "factor 10000000019" \
 testing "3 6 from stdin" "factor" "3: 3\n6: 2 3\n" "" "3 6"
 testing "stdin newline" "factor" "3: 3\n6: 2 3\n" "" "3\n6\n"
 
+testing "-h" "factor -h $(((1<<63)-26))" \
+  "9223372036854775782: 2 3^4 17 23 319279 456065899\n" "" ""
+testing "-x" "factor -x $(((1<<63)-20))" \
+  "7fffffffffffffec: 2 2 3 283 43f2ba978e663\n" "" ""
+

toys/other/factor.c

@@ -3,8 +3,10 @@
  * Copyright 2014 Rob Landley <rob@landley.net>
  *
  * See https://man7.org/linux/man-pages/man1/factor.1.html
+ *
+ * -h and -x options come from https://man.netbsd.org/factor.6
 
-USE_FACTOR(NEWTOY(factor, 0, TOYFLAG_USR|TOYFLAG_BIN))
+USE_FACTOR(NEWTOY(factor, "?hx", TOYFLAG_USR|TOYFLAG_BIN))
 
 config FACTOR
   bool "factor"
@@ -13,17 +15,22 @@ config FACTOR
     usage: factor NUMBER...
 
     Factor integers.
+
+    -h	Human readable: show repeated factors as x^n
+    -x	Hexadecimal output
 */
 
+#define FOR_factor
 #include "toys.h"
 
 static void factor(char *s)
 {
   unsigned long long l, ll, lll;
+  char *pat1 = FLAG(x) ? " %llx" : " %llu", *pat2 = FLAG(x) ? "^%x" : "^%u";
 
   for (;;) {
     char *err = s;
-    int dash = 0;
+    int dash = 0, ii;
 
     while(isspace(*s)) s++;
     if (*s=='-') dash = *s++;
@@ -37,34 +44,25 @@ static void factor(char *s)
       continue;
     }
 
-    printf("-%llu:"+!dash, l);
+    if (dash) xputc('-');
+    printf(pat1+1, l);
+    xputc(':');
 
     // Negative numbers have -1 as a factor
     if (dash) printf(" -1");
 
-    // Nothing below 4 has factors
-    if (l < 4) {
-      printf(" %llu\n", l);
-      continue;
-    }
-
-    // Special case factors of 2
-    while (l && !(l&1)) {
-      printf(" 2");
-      l >>= 1;
-    }
-
-    // test odd numbers until square is > remainder or integer wrap.
-    for (ll = 3;; ll += 2) {
+    // test 2 and odd numbers until square is > remainder or integer wrap.
+    for (ll = 2;; ll += 1+(ll!=2)) {
       lll = ll*ll;
       if (lll>l || lll<ll) {
-        if (l>1) printf(" %llu", l);
+        if (l>1 || ll==2) printf(pat1, l);
         break;
       }
-      while (!(l%ll)) {
-        printf(" %llu", ll);
+      for (ii = 0; !(l%ll); ii++) {
+        if (!ii || !FLAG(h)) printf(pat1, ll);
         l /= ll;
       }
+      if (ii>1 && FLAG(h)) printf(pat2, ii);
     }
     xputc('\n');
   }