diff --git a/serial/tools/list_ports_linux.py b/serial/tools/list_ports_linux.py
index 11092b5..f7491e5 100644
--- a/serial/tools/list_ports_linux.py
+++ b/serial/tools/list_ports_linux.py
@@ -3,64 +3,47 @@
 # portable serial port access with python
 #
 # This is a module that gathers a list of serial ports including details on
-# GNU/Linux systems
+# GNU/Linux systems.
+# The comports function is expected to return an iterable that yields tuples of
+# 3 strings: port name, human readable description and a hardware ID.
 #
 # (C) 2011-2015 Chris Liechti <cliechti@gmx.net>
 #
 # SPDX-License-Identifier:    BSD-3-Clause
 
 import glob
-import sys
 import os
 import re
+import subprocess
+import sys
 
-try:
-    import subprocess
-except ImportError:
-    def popen(argv):
-        try:
-            si, so =  os.popen4(' '.join(argv))
-            return so.read().strip()
-        except:
-            raise IOError('lsusb failed')
-else:
-    def popen(argv):
-        try:
-            return subprocess.check_output(argv, stderr=subprocess.STDOUT).strip()
-        except:
-            raise IOError('lsusb failed')
+def read_command(argv):
+    """run a command and return its output"""
+    try:
+        return subprocess.check_output(argv, stderr=subprocess.STDOUT).strip().decode('ascii', 'replace')
+    except subprocess.SubprocessError as e:
+        raise IOError('command %r failed: %s' % (argv, e))
 
-
-# The comports function is expected to return an iterable that yields tuples of
-# 3 strings: port name, human readable description and a hardware ID.
-#
-# as currently no method is known to get the second two strings easily, they
-# are currently just identical to the port name.
-
-# try to detect the OS so that a device can be selected...
-plat = sys.platform.lower()
-
-def read_line(filename):
+def read_line(*args):
     """\
     Helper function to read a single line from a file.
+    One or more parameters are allowed, they are joined with os.path.join.
     Returns None on errors..
     """
     try:
-        f = open(filename)
-        line = f.readline().strip()
-        f.close()
+        with open(os.path.join(*args)) as f:
+            line = f.readline().strip()
         return line
     except IOError:
         return None
 
 def re_group(regexp, text):
     """search for regexp in text, return 1st group on match"""
-    if sys.version < '3':
-        m = re.search(regexp, text)
+    m = re.search(regexp, text)
+    if m:
+        return m.group(1)
     else:
-        # text is bytes-like
-        m = re.search(regexp, text.decode('ascii', 'replace'))
-    if m: return m.group(1)
+        return None
 
 
 # try to extract descriptions from sysfs. this was done by experimenting,
@@ -69,14 +52,14 @@
 def usb_sysfs_hw_string(sysfs_path):
     """given a path to a usb device in sysfs, return a string describing it"""
     bus, dev = os.path.basename(os.path.realpath(sysfs_path)).split('-')
-    snr = read_line(sysfs_path+'/serial')
-    if snr:
+    snr = read_line(sysfs_path, 'serial')
+    if snr is not None:
         snr_txt = ' SNR=%s' % (snr,)
     else:
         snr_txt = ''
     return 'USB VID:PID=%s:%s%s' % (
-            read_line(sysfs_path+'/idVendor'),
-            read_line(sysfs_path+'/idProduct'),
+            read_line(sysfs_path, 'idVendor'),
+            read_line(sysfs_path, 'idProduct'),
             snr_txt
             )
 
@@ -84,8 +67,11 @@
     base = os.path.basename(os.path.realpath(sysfs_path))
     bus = base.split('-')[0]
     try:
-        dev = int(read_line(os.path.join(sysfs_path, 'devnum')))
-        desc = popen(['lsusb', '-v', '-s', '%s:%s' % (bus, dev)])
+        dev = int(read_line(sysfs_path, 'devnum'))
+        desc = read_command(['lsusb', '-v', '-s', '%s:%s' % (bus, dev)])
+    except IOError:
+        return base
+    else:
         # descriptions from device
         iManufacturer = re_group('iManufacturer\s+\w+ (.+)', desc)
         iProduct = re_group('iProduct\s+\w+ (.+)', desc)
@@ -95,8 +81,6 @@
         idProduct = re_group('idProduct\s+0x\w+ (.+)', desc)
         # create descriptions. prefer text from device, fall back to the others
         return '%s %s %s' % (iManufacturer or idVendor, iProduct or idProduct, iSerial)
-    except IOError:
-        return base
 
 def describe(device):
     """\
@@ -154,3 +138,4 @@
 if __name__ == '__main__':
     for port, desc, hwid in sorted(comports()):
         print("%s: %s [%s]" % (port, desc, hwid))
+