Allow "-ifoo" on the command-line, which is the same as "-ifoo=0"

src/init.c

@@ -936,10 +936,28 @@ static void InitializeVar(char const *str)
 	str++;
     }
     varname[r] = 0;
-    if (!*str) {
-	fprintf(ErrFp, ErrMsg[M_I_OPTION], ErrMsg[E_MISS_EQ]);
+    if (!*varname) {
+	fprintf(ErrFp, ErrMsg[M_I_OPTION], ErrMsg[E_MISS_VAR]);
 	return;
     }
+    if (!*str) {
+        /* Setting a system var does require =expr on the commandline */
+        if (*varname == '$') {
+            fprintf(ErrFp, ErrMsg[M_I_OPTION], ErrMsg[E_MISS_EQ]);
+            return;
+        }
+        val.type = INT_TYPE;
+        val.v.val = 0;
+        r = SetVar(varname, &val);
+        if (!r) {
+            r = PreserveVar(varname);
+        }
+        if (r) {
+            fprintf(ErrFp, ErrMsg[M_I_OPTION], ErrMsg[r]);
+        }
+        return;
+    }
+
     if (!*varname) {
 	fprintf(ErrFp, ErrMsg[M_I_OPTION], ErrMsg[E_MISS_VAR]);
 	return;

tests/test-rem

@@ -541,6 +541,15 @@ EOF
 
 (echo 'BANNER %'; echo 'REM 29 MSG No bug') | ../src/remind -dt - 29 Feb 2024 >> ../tests/test.out 2>&1
 
+../src/remind -ifoo - <<'EOF' >> ../tests/test.out 2>&1
+BANNER %
+DUMP
+EOF
+
+../src/remind '-i$AddBlankLines' - <<'EOF' >> ../tests/test.out 2>&1
+BANNER %
+DUMP
+EOF
 # Remove references to SysInclude, which is build-specific
 grep -F -v '$SysInclude' < ../tests/test.out > ../tests/test.out.1 && mv -f ../tests/test.out.1 ../tests/test.out
 cmp -s ../tests/test.out ../tests/test.cmp

tests/test.cmp

@@ -12001,3 +12001,11 @@ No reminders.
 -(2): Trig = Thursday, 29 February, 2024
 No bug
 
+Variable  Value
+
+foo  0
+No reminders.
+Remind: '-i' option: Missing '=' sign
+Variable  Value
+
+No reminders.