diff --git a/.gitignore b/.gitignore
index 9b810ae..3dc2d95 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,8 @@
 output/
 resource
 *.db
+*2015*
+*2017*
+2020*
+avatar.index
+emoji.cache
diff --git a/common/procutil.py b/common/procutil.py
new file mode 100644
index 0000000..08a5a70
--- /dev/null
+++ b/common/procutil.py
@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+
+import subprocess
+
+def subproc_call(cmd, timeout=None):
+    """
+    Execute a command with timeout, and return STDOUT and STDERR
+
+    Args:
+        cmd(str): the command to execute.
+        timeout(float): timeout in seconds.
+
+    Returns:
+        output(bytes), retcode(int). If timeout, retcode is -1.
+    """
+    try:
+        output = subprocess.check_output(
+            cmd, stderr=subprocess.STDOUT,
+            shell=True, timeout=timeout)
+        return output, 0
+    except subprocess.TimeoutExpired as e:
+        logger.warn("Command '{}' timeout!".format(cmd))
+        if e.output:
+            logger.warn(e.output.decode('utf-8'))
+            return e.output, -1
+        else:
+            return "", -1
+    except subprocess.CalledProcessError as e:
+        logger.warn("Command '{}' failed, return code={}".format(cmd, e.returncode))
+        logger.warn(e.output.decode('utf-8'))
+        return e.output, e.returncode
+    except Exception:
+        logger.warn("Command '{}' failed to run.".format(cmd))
+        return "", -2
+
+
+def subproc_succ(cmd):
+    """
+    Like subproc_call, but expect the cmd to succeed.
+    """
+    output, ret = subproc_call(cmd)
+    assert ret == 0
+    return output
+
+
+