运行 Appium 出现如下错误求解：
debug: executing: "E:\android-sdk-windows\platform-tools\adb.exe" -s emulator-55
54 push "E:\AppiumForWindows-0.12.0\Appium\node_modules\appium\build\andro
id_bootstrap\AppiumBootstrap.jar" /data/local/tmp/
debug: Pushing unlock helper app to device...
debug: executing: "E:\android-sdk-windows\platform-tools\adb.exe" -s emulator-55
54 install E:\AppiumForWindows-0.12.0\Appium\node_modules\appium\build\unlock_ap
k\unlock_apk-debug.apk
info: Attempting to kill all 'uiautomator' processes
info: Getting all processes with 'uiautomator'
debug: executing: "E:\android-sdk-windows\platform-tools\adb.exe" -s emulator-55
54 shell "ps | grep 'uiautomator'"
info: Stopping logcat capture
info: Sent shutdown command, waiting for UiAutomator to stop...
warn: UiAutomator did not shut down fast enough, calling it gone
info: Cleaning up android objects
info: Cleaning up appium session
error: Failed to start an Appium session, err was: Error: Could not extract PIDs
from ps output. PIDS: [], Procs: ["/system/bin/sh: grep: not found"]
info: Responding to client with error: {"status":33,"value":{"message":"A new se
ssion could not be created. (Original error: Could not extract PIDs from ps outp
ut. PIDS: [], Procs: [\"/system/bin/sh: grep: not found\"])","origValue":"Could
not extract PIDs from ps output. PIDS: [], Procs: [\"/system/bin/sh: grep: not f
ound\"]"},"sessionId":null}
POST /wd/hub/session 500 13907ms - 336b