diff --git a/packages/hydrojudge/package.json b/packages/hydrojudge/package.json
index b1350b455..191b1a1dc 100644
--- a/packages/hydrojudge/package.json
+++ b/packages/hydrojudge/package.json
@@ -1,7 +1,10 @@
 {
     "name": "@hydrooj/hydrojudge",
     "bin": "bin/hydrojudge.js",
-    "version": "2.4.3",
+    "version": "2.4.4",
+    "os": [
+        "linux"
+    ],
     "main": "package.json",
     "author": "undefined <i@undefined.moe>",
     "repository": "https://github.com/hydro-dev/Hydro.git",
diff --git a/packages/hydrojudge/src/cases.ts b/packages/hydrojudge/src/cases.ts
index 31b4816a1..899f7b867 100644
--- a/packages/hydrojudge/src/cases.ts
+++ b/packages/hydrojudge/src/cases.ts
@@ -235,8 +235,8 @@ export async function readYamlCases(folder: string, cfg: Dictionary<any> = {}, a
         for (const c of cfg.cases) {
             config.count++;
             config.subtasks[0].cases.push({
-                input: c.input ? checkFile(c.input, 'Cannot find input file {0}.') : null,
-                output: c.output ? checkFile(c.output, 'Cannot find output file {0}.') : null,
+                input: c.input ? checkFile(c.input, 'Cannot find input file {0}.') : '/dev/null',
+                output: c.output ? checkFile(c.output, 'Cannot find output file {0}.') : '/dev/null',
                 id: config.count,
             });
         }
@@ -246,8 +246,8 @@ export async function readYamlCases(folder: string, cfg: Dictionary<any> = {}, a
             for (const c of subtask.cases) {
                 config.count++;
                 cases.push({
-                    input: c.input ? checkFile(c.input, 'Cannot find input file {0}.') : null,
-                    output: c.output ? checkFile(c.output, 'Cannot find output file {0}.') : null,
+                    input: c.input ? checkFile(c.input, 'Cannot find input file {0}.') : '/dev/null',
+                    output: c.output ? checkFile(c.output, 'Cannot find output file {0}.') : '/dev/null',
                     id: config.count,
                 });
             }
diff --git a/packages/hydrojudge/src/judge/interactive.ts b/packages/hydrojudge/src/judge/interactive.ts
index 60f043f9b..d8c11e394 100644
--- a/packages/hydrojudge/src/judge/interactive.ts
+++ b/packages/hydrojudge/src/judge/interactive.ts
@@ -111,6 +111,7 @@ export const judge = async (ctx) => {
             );
         })(),
     ]);
+    ctx.clean.push(ctx.executeUser.clean, ctx.executeInteractor.clean);
     ctx.next({ status: STATUS.STATUS_JUDGING, progress: 0 });
     const tasks = [];
     ctx.total_status = ctx.total_score = ctx.total_memory_usage_kb = ctx.total_time_usage_ms = 0;
diff --git a/packages/hydrojudge/src/sandbox.ts b/packages/hydrojudge/src/sandbox.ts
index 63c670646..64a2e1674 100644
--- a/packages/hydrojudge/src/sandbox.ts
+++ b/packages/hydrojudge/src/sandbox.ts
@@ -10,6 +10,7 @@ import { Logger } from './log';
 const logger = new Logger('sandbox');
 const env = ['PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin', 'HOME=/w'];
 const axios = Axios.create({ baseURL: getConfig('sandbox_host') });
+let callId = 0;
 
 const statusMap = {
     'Time Limit Exceeded': STATUS.STATUS_TIME_LIMIT_EXCEEDED,
@@ -90,9 +91,10 @@ export async function runMultiple(execute) {
         body.cmd[0].files[1] = null;
         body.cmd[1].files[0] = null;
         body.cmd[1].files[1] = null;
-        if (argv['show-sandbox-call']) logger.debug(JSON.stringify(body));
+        const id = callId++;
+        if (argv['show-sandbox-call']) logger.debug('%d %s', id, JSON.stringify(body));
         res = await axios.post('/run', body);
-        if (argv['show-sandbox-call']) logger.debug(JSON.stringify(res.data));
+        if (argv['show-sandbox-call']) logger.debug('%d %s', id, JSON.stringify(res.data));
     } catch (e) {
         throw new SystemError('Sandbox Error');
     }
@@ -111,9 +113,10 @@ export async function run(execute, params?) {
     if (typeof execute === 'object') return await runMultiple(execute);
     try {
         const body = { cmd: [proc({ execute, ...params })] };
-        if (argv['show-sandbox-call']) logger.debug(JSON.stringify(body));
+        const id = callId++;
+        if (argv['show-sandbox-call']) logger.debug('%d %s', id, JSON.stringify(body));
         const res = await axios.post('/run', body);
-        if (argv['show-sandbox-call']) logger.debug(JSON.stringify(res.data));
+        if (argv['show-sandbox-call']) logger.debug('%d %s', id, JSON.stringify(res.data));
         [result] = res.data;
     } catch (e) {
         // FIXME request body larger than maxBodyLength limit