[celestica] consutil to support customize tty device name (#1155)

* Update lib.py
* Keep the code format align see add spaces for special symbols
* remove unused code

Author: sandycelestica

consutil/lib.py

@@ -10,7 +10,9 @@
     import re
     import subprocess
     import sys
+    import os
     from swsssdk import ConfigDBConnector
+    from sonic_py_common import device_info
 except ImportError as e:
     raise ImportError("%s - required module not found" % str(e))
 
@@ -27,6 +29,8 @@
 FLOW_KEY = "flow_control"
 DEFAULT_BAUD = "9600"
 
+FILENAME = "udevprefix.conf"
+
 # QUIET == True => picocom will not output any messages, and pexpect will wait for console
 #                  switch login or command line to let user interact with shell
 #        Downside: if console switch output ever does not match DEV_READY_MSG, program will think connection failed
@@ -37,6 +41,15 @@
 DEV_READY_MSG = r"([Ll]ogin:|[Pp]assword:|[$>#])" # login prompt or command line prompt
 TIMEOUT_SEC = 0.2
 
+platform_path, _ = device_info.get_paths_to_platform_and_hwsku_dirs()
+PLUGIN_PATH = "/".join([platform_path, "plugins", FILENAME])
+
+if os.path.exists(PLUGIN_PATH):
+    fp = open(PLUGIN_PATH, 'r')
+    line = fp.readlines()
+    DEVICE_PREFIX = "/dev/" + line[0]
+
+
 # runs command, exit if stderr is written to, returns stdout otherwise
 # input: cmd (str), output: output of cmd (str)
 def run_command(cmd):
@@ -119,4 +132,4 @@ def getLine(target, deviceBool=False):
             lineNumber = line[LINE_KEY]
             targetLine = line
 
-    return targetLine if lineNumber else None
+    return targetLine if lineNumber else None