networkd-tests.py: add helpers to common subprocess call patterns

For normal shell calls, python syntax is quite verbose. We don't need to punish
ourselves like that. In some places we would fork a shell to do argument splitting
for us. We know that our arguments can be safely split on whitespace, so let's do
that ourselves in all cases, without forking a shell.

We also expect command output to be valid text, so let's always set
universal_newlines=True.

This makes things shorter and easier to read. Development is also easier because
it's possible to paste many of the commands directly to/from a shell.

diff --git a/test/test-network/systemd-networkd-tests.py b/test/test-network/systemd-networkd-tests.py
index 34143012e4948f5efb570ce0b2a4fb4c1f278206..57f930a2ec2c8df091951334460cb21853d85b29 100755 (executable)
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -32,10 +32,23 @@ asan_options=None
 lsan_options=None
 ubsan_options=None
 
+def check_output(*command, **kwargs):
+    # This replaces both check_output and check_call (output can be ignored)
+    command = command[0].split() + list(command[1:])
+    return subprocess.check_output(command, universal_newlines=True, **kwargs).rstrip()
+
+def call(*command, **kwargs):
+    command = command[0].split() + list(command[1:])
+    return subprocess.call(command, universal_newlines=True, **kwargs)
+
+def run(*command, **kwargs):
+    command = command[0].split() + list(command[1:])
+    return subprocess.run(command, universal_newlines=True, **kwargs)
+
 def is_module_available(module_name):
-    lsmod_output = subprocess.check_output('lsmod', universal_newlines=True)
-    module_re = re.compile(r'^{0}\b'.format(re.escape(module_name)), re.MULTILINE)
-    return module_re.search(lsmod_output) or not subprocess.call(["modprobe", module_name])
+    lsmod_output = check_output('lsmod')
+    module_re = re.compile(rf'^{re.escape(module_name)}\b', re.MULTILINE)
+    return module_re.search(lsmod_output) or not call('modprobe', module_name)
 
 def expectedFailureIfModuleIsNotAvailable(module_name):
     def f(func):
@@ -47,9 +60,9 @@ def expectedFailureIfModuleIsNotAvailable(module_name):
 
 def expectedFailureIfERSPANModuleIsNotAvailable():
     def f(func):
-        rc = subprocess.call(['ip', 'link', 'add', 'dev', 'erspan99', 'type', 'erspan', 'seq', 'key', '30', 'local', '192.168.1.4', 'remote', '192.168.1.1', 'erspan_ver', '1', 'erspan', '123'])
+        rc = call('ip link add dev erspan99 type erspan seq key 30 local 192.168.1.4 remote 192.168.1.1 erspan_ver 1 erspan 123')
         if rc == 0:
-            subprocess.call(['ip', 'link', 'del', 'erspan99'])
+            call('ip link del erspan99')
             return func
         else:
             return unittest.expectedFailure(func)
@@ -58,9 +71,9 @@ def expectedFailureIfERSPANModuleIsNotAvailable():
 
 def expectedFailureIfRoutingPolicyPortRangeIsNotAvailable():
     def f(func):
-        rc = subprocess.call(['ip', 'rule', 'add', 'from', '192.168.100.19', 'sport', '1123-1150', 'dport', '3224-3290', 'table', '7'])
+        rc = call('ip rule add from 192.168.100.19 sport 1123-1150 dport 3224-3290 table 7')
         if rc == 0:
-            subprocess.call(['ip', 'rule', 'del', 'from', '192.168.100.19', 'sport', '1123-1150', 'dport', '3224-3290', 'table', '7'])
+            call('ip rule del from 192.168.100.19 sport 1123-1150 dport 3224-3290 table 7')
             return func
         else:
             return unittest.expectedFailure(func)
@@ -69,9 +82,9 @@ def expectedFailureIfRoutingPolicyPortRangeIsNotAvailable():
 
 def expectedFailureIfRoutingPolicyIPProtoIsNotAvailable():
     def f(func):
-        rc = subprocess.call(['ip', 'rule', 'add', 'not', 'from', '192.168.100.19', 'ipproto', 'tcp', 'table', '7'])
+        rc = call('ip rule add not from 192.168.100.19 ipproto tcp table 7')
         if rc == 0:
-            subprocess.call(['ip', 'rule', 'del', 'not', 'from', '192.168.100.19', 'ipproto', 'tcp', 'table', '7'])
+            call('ip rule del not from 192.168.100.19 ipproto tcp table 7')
             return func
         else:
             return unittest.expectedFailure(func)
@@ -81,12 +94,12 @@ def expectedFailureIfRoutingPolicyIPProtoIsNotAvailable():
 def expectedFailureIfEthtoolDoesNotSupportDriver():
     def f(func):
         support = False
-        rc = subprocess.call(['ip', 'link', 'add', 'name', 'dummy99', 'type', 'dummy'])
+        rc = call('ip link add name dummy99 type dummy')
         if rc == 0:
-            ret = subprocess.run(['udevadm', 'info', '-w10s', '/sys/class/net/dummy99'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, universal_newlines=True)
+            ret = run('udevadm info -w10s /sys/class/net/dummy99', stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
             if ret.returncode == 0 and 'E: ID_NET_DRIVER=dummy' in ret.stdout.rstrip():
                 support = True
-            subprocess.call(['ip', 'link', 'del', 'dummy99'])
+            call('ip link del dummy99')
 
         if support:
             return func
@@ -102,8 +115,8 @@ def setUpModule():
     shutil.rmtree(networkd_ci_path)
     copytree(os.path.join(os.path.dirname(os.path.abspath(__file__)), 'conf'), networkd_ci_path)
 
-    subprocess.check_call('systemctl stop systemd-networkd.socket', shell=True)
-    subprocess.check_call('systemctl stop systemd-networkd.service', shell=True)
+    check_output('systemctl stop systemd-networkd.socket')
+    check_output('systemctl stop systemd-networkd.service')
 
     drop_in = [
         '[Service]',
@@ -134,20 +147,19 @@ def setUpModule():
     with open('/run/systemd/system/systemd-networkd.service.d/00-override.conf', mode='w') as f:
         f.write('\n'.join(drop_in))
 
-    subprocess.check_call('systemctl daemon-reload', shell=True)
-    output = subprocess.check_output(['systemctl', 'cat', 'systemd-networkd.service'], universal_newlines=True).rstrip()
-    print(output)
+    check_output('systemctl daemon-reload')
+    print(check_output('systemctl cat systemd-networkd.service'))
 
 def tearDownModule():
     shutil.rmtree(networkd_ci_path)
 
-    subprocess.check_call('systemctl stop systemd-networkd.service', shell=True)
+    check_output('systemctl stop systemd-networkd.service')
 
     shutil.rmtree('/run/systemd/system/systemd-networkd.service.d')
-    subprocess.check_call('systemctl daemon-reload', shell=True)
+    check_output('systemctl daemon-reload')
 
-    subprocess.check_call('systemctl start systemd-networkd.socket', shell=True)
-    subprocess.check_call('systemctl start systemd-networkd.service', shell=True)
+    check_output('systemctl start systemd-networkd.socket')
+    check_output('systemctl start systemd-networkd.service')
 
 class Utilities():
     def read_link_attr(self, link, dev, attribute):
@@ -172,27 +184,27 @@ class Utilities():
     def remove_links(self, links):
         for link in links:
             if self.link_exists(link):
-                subprocess.call(['ip', 'link', 'del', 'dev', link])
+                call('ip link del dev', link)
         time.sleep(1)
 
     def remove_fou_ports(self, ports):
         for port in ports:
-            subprocess.call(['ip', 'fou', 'del', 'port', port])
+            call('ip fou del port', port)
 
     def remove_routing_policy_rule_tables(self, tables):
         for table in tables:
-            subprocess.call(['ip', 'rule', 'del', 'table', table])
+            call('ip rule del table', table)
 
     def remove_routes(self, routes):
         for route_type, addr in routes:
-            subprocess.call(['ip', 'route', 'del', route_type, addr])
+            call('ip route del', route_type, addr)
 
     def l2tp_tunnel_remove(self, tunnel_ids):
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'tunnel'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show tunnel')
         for tid in tunnel_ids:
             words='Tunnel ' + tid + ', encap'
             if words in output:
-                subprocess.call(['ip', 'l2tp', 'del', 'tunnel', 'tid', tid])
+                call('ip l2tp del tunnel tid', tid)
         time.sleep(1)
 
     def read_ipv6_sysctl_attr(self, link, attribute):
@@ -218,14 +230,14 @@ class Utilities():
                     shutil.rmtree(os.path.join(network_unit_file_path, unit + '.d'))
 
     def warn_about_firewalld(self):
-        rc = subprocess.call(['systemctl', '-q', 'is-active', 'firewalld.service'])
+        rc = call('systemctl -q is-active firewalld.service')
         if rc == 0:
             print('\nWARNING: firewalld.service is active. The test may fail.')
 
     def start_dnsmasq(self, additional_options='', ipv4_range='192.168.5.10,192.168.5.200', ipv6_range='2600::10,2600::20', lease_time='1h'):
         self.warn_about_firewalld()
         dnsmasq_command = f'dnsmasq -8 /var/run/networkd-ci/test-dnsmasq-log-file --log-queries=extra --log-dhcp --pid-file=/var/run/networkd-ci/test-test-dnsmasq.pid --conf-file=/dev/null --interface=veth-peer --enable-ra --dhcp-range={ipv6_range},{lease_time} --dhcp-range={ipv4_range},{lease_time} -R --dhcp-leasefile=/var/run/networkd-ci/lease --dhcp-option=26,1492 --dhcp-option=option:router,192.168.5.1 --dhcp-option=33,192.168.5.4,192.168.5.5 --port=0 ' + additional_options
-        subprocess.check_call(dnsmasq_command, shell=True)
+        check_output(dnsmasq_command)
 
     def stop_dnsmasq(self, pid_file):
         if os.path.exists(pid_file):
@@ -259,11 +271,11 @@ class Utilities():
     def start_networkd(self, sleep_sec=5, remove_state_files=True):
         if (remove_state_files and
             os.path.exists(os.path.join(networkd_runtime_directory, 'state'))):
-            subprocess.check_call('systemctl stop systemd-networkd', shell=True)
+            check_output('systemctl stop systemd-networkd')
             os.remove(os.path.join(networkd_runtime_directory, 'state'))
-            subprocess.check_call('systemctl start systemd-networkd', shell=True)
+            check_output('systemctl start systemd-networkd')
         else:
-            subprocess.check_call('systemctl restart systemd-networkd', shell=True)
+            check_output('systemctl restart systemd-networkd')
         if sleep_sec > 0:
             time.sleep(sleep_sec)
 
@@ -272,15 +284,15 @@ class Utilities():
         if bool_any:
             args += ['--any']
         try:
-            subprocess.check_call(args, env=env)
+            check_output(*args, env=env)
         except subprocess.CalledProcessError:
             for link in links_with_operstate:
-                output = subprocess.check_output(networkctl_cmd + ['status', link.split(':')[0]], universal_newlines=True, env=env).rstrip()
+                output = check_output(*networkctl_cmd, 'status', link.split(':')[0], env=env)
                 print(output)
             raise
 
     def get_operstate(self, link, show_status=True, setup_state='configured'):
-        output = subprocess.check_output(networkctl_cmd + ['status', link], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', link, env=env)
         if show_status:
             print(output)
         for line in output.splitlines():
@@ -295,7 +307,7 @@ class Utilities():
         for i in range(timeout_sec):
             if i > 0:
                 time.sleep(1)
-            output = subprocess.check_output(['ip', ipv, 'address', 'show', 'dev', link, 'scope', scope], universal_newlines=True).rstrip()
+            output = check_output(f'ip {ipv} address show dev {link} scope {scope}')
             if re.search(address_regex, output):
                 break
         else:
@@ -329,23 +341,23 @@ class NetworkctlTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded'])
 
-        output = subprocess.check_output(networkctl_cmd + ['list'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'list', env=env)
         self.assertRegex(output, '1 lo ')
         self.assertRegex(output, 'test1')
 
-        output = subprocess.check_output(networkctl_cmd + ['list', 'test1'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'list', 'test1', env=env)
         self.assertNotRegex(output, '1 lo ')
         self.assertRegex(output, 'test1')
 
-        output = subprocess.check_output(networkctl_cmd + ['list', 'te*'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'list', 'te*', env=env)
         self.assertNotRegex(output, '1 lo ')
         self.assertRegex(output, 'test1')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'te*'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'te*', env=env)
         self.assertNotRegex(output, '1: lo ')
         self.assertRegex(output, 'test1')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'tes[a-z][0-9]'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'tes[a-z][0-9]', env=env)
         self.assertNotRegex(output, '1: lo ')
         self.assertRegex(output, 'test1')
 
@@ -355,7 +367,7 @@ class NetworkctlTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'test1'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'test1', env=env)
         self.assertRegex(output, 'MTU: 1600')
 
     @expectedFailureIfEthtoolDoesNotSupportDriver()
@@ -366,13 +378,13 @@ class NetworkctlTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded', 'veth99:degraded', 'veth-peer:degraded'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'test1'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'test1', env=env)
         self.assertRegex(output, 'Driver: dummy')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         self.assertRegex(output, 'Driver: veth')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth-peer'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth-peer', env=env)
         self.assertRegex(output, 'Driver: veth')
 
     def test_delete_links(self):
@@ -382,7 +394,7 @@ class NetworkctlTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded', 'veth99:degraded', 'veth-peer:degraded'])
 
-        subprocess.check_call(networkctl_cmd + ['delete', 'test1', 'veth99'])
+        check_output(*networkctl_cmd, 'delete', 'test1', 'veth99')
         self.assertFalse(self.link_exists('test1'))
         self.assertFalse(self.link_exists('veth99'))
         self.assertFalse(self.link_exists('veth-peer'))
@@ -560,7 +572,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['dropin-test:off'])
 
-        output = subprocess.check_output(['ip', 'link', 'show', 'dropin-test'], universal_newlines=True).rstrip()
+        output = check_output('ip link show dropin-test')
         print(output)
         self.assertRegex(output, '00:50:56:c0:00:28')
 
@@ -617,11 +629,11 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded', 'vlan99:routable'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show test1')
         print(output)
         self.assertRegex(output, ' mtu 2000 ')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vlan99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vlan99')
         print(output)
         self.assertRegex(output, ' mtu 2000 ')
         self.assertRegex(output, 'REORDER_HDR')
@@ -630,12 +642,12 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.assertRegex(output, 'MVRP')
         self.assertRegex(output, ' id 99 ')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev test1')
         print(output)
         self.assertRegex(output, 'inet 192.168.24.5/24 brd 192.168.24.255 scope global test1')
         self.assertRegex(output, 'inet 192.168.25.5/24 brd 192.168.25.255 scope global test1')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'vlan99'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev vlan99')
         print(output)
         self.assertRegex(output, 'inet 192.168.23.5/24 brd 192.168.23.255 scope global vlan99')
 
@@ -652,7 +664,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
                 self.wait_online(['macvtap99:degraded', 'test1:degraded'])
 
-                output = subprocess.check_output(['ip', '-d', 'link', 'show', 'macvtap99'], universal_newlines=True).rstrip()
+                output = check_output('ip -d link show macvtap99')
                 print(output)
                 self.assertRegex(output, 'macvtap mode ' + mode + ' ')
 
@@ -669,11 +681,11 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
                 self.wait_online(['macvlan99:degraded', 'test1:degraded'])
 
-                output = subprocess.check_output(['ip', '-d', 'link', 'show', 'test1'], universal_newlines=True).rstrip()
+                output = check_output('ip -d link show test1')
                 print(output)
                 self.assertRegex(output, ' mtu 2000 ')
 
-                output = subprocess.check_output(['ip', '-d', 'link', 'show', 'macvlan99'], universal_newlines=True).rstrip()
+                output = check_output('ip -d link show macvlan99')
                 print(output)
                 self.assertRegex(output, ' mtu 2000 ')
                 self.assertRegex(output, 'macvlan mode ' + mode + ' ')
@@ -692,7 +704,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
                 self.start_networkd(0)
                 self.wait_online(['ipvlan99:degraded', 'test1:degraded'])
 
-                output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipvlan99'], universal_newlines=True).rstrip()
+                output = check_output('ip -d link show ipvlan99')
                 print(output)
                 self.assertRegex(output, 'ipvlan  *mode ' + mode.lower() + ' ' + flag)
 
@@ -710,7 +722,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
                 self.start_networkd(0)
                 self.wait_online(['ipvtap99:degraded', 'test1:degraded'])
 
-                output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipvtap99'], universal_newlines=True).rstrip()
+                output = check_output('ip -d link show ipvtap99')
                 print(output)
                 self.assertRegex(output, 'ipvtap  *mode ' + mode.lower() + ' ' + flag)
 
@@ -720,10 +732,10 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['veth99:degraded', 'veth-peer:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show veth99')
         print(output)
         self.assertRegex(output, 'link/ether 12:34:56:78:9a:bc')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'veth-peer'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show veth-peer')
         print(output)
         self.assertRegex(output, 'link/ether 12:34:56:78:9a:bd')
 
@@ -733,7 +745,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['tun99:off'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'tun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show tun99')
         print(output)
         # Old ip command does not support IFF_ flags
         self.assertRegex(output, 'tun (?:type tun pi on vnet_hdr on multi_queue|addrgenmode) ')
@@ -744,7 +756,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['tap99:off'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'tap99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show tap99')
         print(output)
         # Old ip command does not support IFF_ flags
         self.assertRegex(output, 'tun (?:type tap pi on vnet_hdr on multi_queue|addrgenmode) ')
@@ -779,26 +791,26 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.wait_online(['wg99:carrier', 'wg98:routable'])
 
         if shutil.which('wg'):
-            subprocess.call('wg')
+            call('wg')
 
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'listen-port'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 listen-port')
             self.assertRegex(output, '51820')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'fwmark'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 fwmark')
             self.assertRegex(output, '0x4d2')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'allowed-ips'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 allowed-ips')
             self.assertRegex(output, 'RDf\+LSpeEre7YEIKaxg\+wbpsNV7du\+ktR99uBEtIiCA=\t192.168.26.0/24 fd31:bf08:57cb::/48')
             self.assertRegex(output, 'lsDtM3AbjxNlauRKzHEPfgS1Zp7cp/VX5Use/P4PQSc=\tfdbc:bae2:7871:e1fe:793:8636::/96 fdbc:bae2:7871:500:e1fe:793:8636:dad1/128')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'persistent-keepalive'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 persistent-keepalive')
             self.assertRegex(output, 'RDf\+LSpeEre7YEIKaxg\+wbpsNV7du\+ktR99uBEtIiCA=\t20')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'endpoints'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 endpoints')
             self.assertRegex(output, 'RDf\+LSpeEre7YEIKaxg\+wbpsNV7du\+ktR99uBEtIiCA=\t192.168.27.3:51820')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'private-key'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 private-key')
             self.assertRegex(output, 'EEGlnEPYJV//kbvvIqxKkQwOiS\+UENyPncC4bF46ong=')
-            output = subprocess.check_output(['wg', 'show', 'wg99', 'preshared-keys'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg99 preshared-keys')
             self.assertRegex(output, 'RDf\+LSpeEre7YEIKaxg\+wbpsNV7du\+ktR99uBEtIiCA=  IIWIV17wutHv7t4cR6pOT91z6NSz/T8Arh0yaywhw3M=')
             self.assertRegex(output, 'lsDtM3AbjxNlauRKzHEPfgS1Zp7cp/VX5Use/P4PQSc=     cPLOy1YUrEI0EMMIycPJmOo0aTu3RZnw8bL5meVD6m0=')
 
-            output = subprocess.check_output(['wg', 'show', 'wg98', 'private-key'], universal_newlines=True).rstrip()
+            output = check_output('wg show wg98 private-key')
             self.assertRegex(output, 'CJQUtcS9emY2fLYqDlpSZiE/QJyHkPWr\+WHtZLZ90FU=')
 
     def test_geneve(self):
@@ -807,7 +819,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['geneve99:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'geneve99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show geneve99')
         print(output)
         self.assertRegex(output, '192.168.22.1')
         self.assertRegex(output, '6082')
@@ -822,13 +834,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['ipiptun99:routable', 'ipiptun98:routable', 'ipiptun97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipiptun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ipiptun99')
         print(output)
         self.assertRegex(output, 'ipip (?:ipip |)remote 192.169.224.239 local 192.168.223.238 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipiptun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ipiptun98')
         print(output)
         self.assertRegex(output, 'ipip (?:ipip |)remote 192.169.224.239 local any dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipiptun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ipiptun97')
         print(output)
         self.assertRegex(output, 'ipip (?:ipip |)remote any local 192.168.223.238 dev dummy98')
 
@@ -840,21 +852,21 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['gretun99:routable', 'gretun98:routable', 'gretun97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretun99')
         print(output)
         self.assertRegex(output, 'gre remote 10.65.223.239 local 10.65.223.238 dev dummy98')
         self.assertRegex(output, 'ikey 1.2.3.103')
         self.assertRegex(output, 'okey 1.2.4.103')
         self.assertRegex(output, 'iseq')
         self.assertRegex(output, 'oseq')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretun98')
         print(output)
         self.assertRegex(output, 'gre remote 10.65.223.239 local any dev dummy98')
         self.assertRegex(output, 'ikey 0.0.0.104')
         self.assertRegex(output, 'okey 0.0.0.104')
         self.assertNotRegex(output, 'iseq')
         self.assertNotRegex(output, 'oseq')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretun97')
         print(output)
         self.assertRegex(output, 'gre remote any local 10.65.223.238 dev dummy98')
         self.assertRegex(output, 'ikey 0.0.0.105')
@@ -876,13 +888,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.check_link_exists('ip6gretun98')
         self.check_link_exists('ip6gretun97')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6gretun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6gretun99')
         print(output)
         self.assertRegex(output, 'ip6gre remote 2001:473:fece:cafe::5179 local 2a00:ffde:4567:edde::4987 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6gretun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6gretun98')
         print(output)
         self.assertRegex(output, 'ip6gre remote 2001:473:fece:cafe::5179 local any dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6gretun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6gretun97')
         print(output)
         self.assertRegex(output, 'ip6gre remote any local 2a00:ffde:4567:edde::4987 dev dummy98')
 
@@ -893,14 +905,14 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['gretap99:routable', 'gretap98:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretap99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretap99')
         print(output)
         self.assertRegex(output, 'gretap remote 10.65.223.239 local 10.65.223.238 dev dummy98')
         self.assertRegex(output, 'ikey 0.0.0.106')
         self.assertRegex(output, 'okey 0.0.0.106')
         self.assertRegex(output, 'iseq')
         self.assertRegex(output, 'oseq')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretap98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretap98')
         print(output)
         self.assertRegex(output, 'gretap remote 10.65.223.239 local any dev dummy98')
         self.assertRegex(output, 'ikey 0.0.0.107')
@@ -915,10 +927,10 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['ip6gretap99:routable', 'ip6gretap98:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6gretap99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6gretap99')
         print(output)
         self.assertRegex(output, 'ip6gretap remote 2001:473:fece:cafe::5179 local 2a00:ffde:4567:edde::4987 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6gretap98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6gretap98')
         print(output)
         self.assertRegex(output, 'ip6gretap remote 2001:473:fece:cafe::5179 local any dev dummy98')
 
@@ -930,13 +942,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['vtitun99:routable', 'vtitun98:routable', 'vtitun97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vtitun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vtitun99')
         print(output)
         self.assertRegex(output, 'vti remote 10.65.223.239 local 10.65.223.238 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vtitun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vtitun98')
         print(output)
         self.assertRegex(output, 'vti remote 10.65.223.239 local any dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vtitun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vtitun97')
         print(output)
         self.assertRegex(output, 'vti remote any local 10.65.223.238 dev dummy98')
 
@@ -948,13 +960,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['vti6tun99:routable', 'vti6tun98:routable', 'vti6tun97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vti6tun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vti6tun99')
         print(output)
         self.assertRegex(output, 'vti6 remote 2001:473:fece:cafe::5179 local 2a00:ffde:4567:edde::4987 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vti6tun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vti6tun98')
         print(output)
         self.assertRegex(output, 'vti6 remote 2001:473:fece:cafe::5179 local (?:any|::) dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vti6tun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vti6tun97')
         print(output)
         self.assertRegex(output, 'vti6 remote (?:any|::) local 2a00:ffde:4567:edde::4987 dev dummy98')
 
@@ -966,13 +978,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['ip6tnl99:routable', 'ip6tnl98:routable', 'ip6tnl97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6tnl99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6tnl99')
         print(output)
         self.assertRegex(output, 'ip6tnl ip6ip6 remote 2001:473:fece:cafe::5179 local 2a00:ffde:4567:edde::4987 dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6tnl98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6tnl98')
         print(output)
         self.assertRegex(output, 'ip6tnl ip6ip6 remote 2001:473:fece:cafe::5179 local (?:any|::) dev dummy98')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ip6tnl97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ip6tnl97')
         print(output)
         self.assertRegex(output, 'ip6tnl ip6ip6 remote (?:any|::) local 2a00:ffde:4567:edde::4987 dev dummy98')
 
@@ -984,13 +996,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['sittun99:routable', 'sittun98:routable', 'sittun97:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'sittun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show sittun99')
         print(output)
         self.assertRegex(output, "sit (?:ip6ip |)remote 10.65.223.239 local 10.65.223.238 dev dummy98")
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'sittun98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show sittun98')
         print(output)
         self.assertRegex(output, "sit (?:ip6ip |)remote 10.65.223.239 local any dev dummy98")
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'sittun97'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show sittun97')
         print(output)
         self.assertRegex(output, "sit (?:ip6ip |)remote any local 10.65.223.238 dev dummy98")
 
@@ -1000,7 +1012,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['isataptun99:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'isataptun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show isataptun99')
         print(output)
         self.assertRegex(output, "isatap ")
 
@@ -1010,7 +1022,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['sittun99:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'sittun99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show sittun99')
         print(output)
         self.assertRegex(output, '6rd-prefix 2602::/24')
 
@@ -1022,14 +1034,14 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['erspan99:routable', 'erspan98:routable', 'dummy98:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'erspan99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show erspan99')
         print(output)
         self.assertRegex(output, 'erspan remote 172.16.1.100 local 172.16.1.200')
         self.assertRegex(output, 'ikey 0.0.0.101')
         self.assertRegex(output, 'okey 0.0.0.101')
         self.assertRegex(output, 'iseq')
         self.assertRegex(output, 'oseq')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'erspan98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show erspan98')
         print(output)
         self.assertRegex(output, 'erspan remote 172.16.1.100 local any')
         self.assertRegex(output, '102')
@@ -1057,21 +1069,21 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['ipiptun96:off', 'sittun96:off', 'gretun96:off', 'gretap96:off'])
 
-        output = subprocess.check_output(['ip', 'fou', 'show'], universal_newlines=True).rstrip()
+        output = check_output('ip fou show')
         print(output)
         self.assertRegex(output, 'port 55555 ipproto 4')
         self.assertRegex(output, 'port 55556 ipproto 47')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'ipiptun96'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show ipiptun96')
         print(output)
         self.assertRegex(output, 'encap fou encap-sport auto encap-dport 55555')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'sittun96'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show sittun96')
         print(output)
         self.assertRegex(output, 'encap fou encap-sport auto encap-dport 55555')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretun96'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretun96')
         print(output)
         self.assertRegex(output, 'encap fou encap-sport 1001 encap-dport 55556')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'gretap96'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show gretap96')
         print(output)
         self.assertRegex(output, 'encap fou encap-sport auto encap-dport 55556')
 
@@ -1082,7 +1094,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:degraded', 'vxlan99:degraded'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'vxlan99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show vxlan99')
         print(output)
         self.assertRegex(output, '999')
         self.assertRegex(output, '5555')
@@ -1095,7 +1107,7 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
         self.assertRegex(output, 'remcsumrx')
         self.assertRegex(output, 'gbp')
 
-        output = subprocess.check_output(['bridge', 'fdb', 'show', 'dev', 'vxlan99'], universal_newlines=True).rstrip()
+        output = check_output('bridge fdb show dev vxlan99')
         print(output)
         self.assertRegex(output, '00:11:22:33:44:55 dst 10.0.0.5 self permanent')
         self.assertRegex(output, '00:11:22:33:44:66 dst 10.0.0.6 self permanent')
@@ -1108,13 +1120,13 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
         self.wait_online(['dummy98:degraded', 'macsec99:routable'])
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'macsec99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show macsec99')
         print(output)
         self.assertRegex(output, 'macsec99@dummy98')
         self.assertRegex(output, 'macsec sci [0-9a-f]*000b')
         self.assertRegex(output, 'encrypt on')
 
-        output = subprocess.check_output(['ip', 'macsec', 'show', 'macsec99'], universal_newlines=True).rstrip()
+        output = check_output('ip macsec show macsec99')
         print(output)
         self.assertRegex(output, 'encrypt on')
         self.assertRegex(output, 'TXSC: [0-9a-f]*000b on SA 1')
@@ -1168,7 +1180,7 @@ class NetworkdL2TPTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:routable', 'l2tp-ses1:off', 'l2tp-ses2:off'])
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'tunnel', 'tunnel_id', '10'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show tunnel tunnel_id 10')
         print(output)
         self.assertRegex(output, "Tunnel 10, encap UDP")
         self.assertRegex(output, "From 192.168.30.100 to 192.168.30.101")
@@ -1176,13 +1188,13 @@ class NetworkdL2TPTests(unittest.TestCase, Utilities):
         self.assertRegex(output, "UDP source / dest ports: 3000/4000")
         self.assertRegex(output, "UDP checksum: enabled")
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'session', 'tid', '10', 'session_id', '15'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show session tid 10 session_id 15')
         print(output)
         self.assertRegex(output, "Session 15 in tunnel 10")
         self.assertRegex(output, "Peer session 16, tunnel 11")
         self.assertRegex(output, "interface name: l2tp-ses1")
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'session', 'tid', '10', 'session_id', '17'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show session tid 10 session_id 17')
         print(output)
         self.assertRegex(output, "Session 17 in tunnel 10")
         self.assertRegex(output, "Peer session 18, tunnel 11")
@@ -1195,19 +1207,19 @@ class NetworkdL2TPTests(unittest.TestCase, Utilities):
 
         self.wait_online(['test1:routable', 'l2tp-ses3:off', 'l2tp-ses4:off'])
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'tunnel', 'tunnel_id', '10'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show tunnel tunnel_id 10')
         print(output)
         self.assertRegex(output, "Tunnel 10, encap IP")
         self.assertRegex(output, "From 192.168.30.100 to 192.168.30.101")
         self.assertRegex(output, "Peer tunnel 12")
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'session', 'tid', '10', 'session_id', '25'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show session tid 10 session_id 25')
         print(output)
         self.assertRegex(output, "Session 25 in tunnel 10")
         self.assertRegex(output, "Peer session 26, tunnel 12")
         self.assertRegex(output, "interface name: l2tp-ses3")
 
-        output = subprocess.check_output(['ip', 'l2tp', 'show', 'session', 'tid', '10', 'session_id', '27'], universal_newlines=True).rstrip()
+        output = check_output('ip l2tp show session tid 10 session_id 27')
         print(output)
         self.assertRegex(output, "Session 27 in tunnel 10")
         self.assertRegex(output, "Peer session 28, tunnel 12")
@@ -1265,7 +1277,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.wait_online(['dummy98:routable'])
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev dummy98')
         print(output)
         self.assertRegex(output, 'inet 10.1.2.3/16 brd 10.1.255.255 scope global dummy98')
         self.assertRegex(output, 'inet 10.1.2.4/16 brd 10.1.255.255 scope global secondary dummy98')
@@ -1275,19 +1287,19 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.assertNotRegex(output, '10.10.0.1/16')
         self.assertNotRegex(output, '10.10.0.2/16')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'dummy98', 'label', '32'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev dummy98 label 32')
         self.assertRegex(output, 'inet 10.3.2.3/16 brd 10.3.255.255 scope global 32')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'dummy98', 'label', '33'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev dummy98 label 33')
         self.assertRegex(output, 'inet 10.4.2.3 peer 10.4.2.4/16 scope global 33')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'dummy98', 'label', '34'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev dummy98 label 34')
         self.assertRegex(output, 'inet 192.168.[0-9]*.1/24 brd 192.168.[0-9]*.255 scope global 34')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'dummy98', 'label', '35'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev dummy98 label 35')
         self.assertRegex(output, 'inet 172.[0-9]*.0.1/16 brd 172.[0-9]*.255.255 scope global 35')
 
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev dummy98')
         print(output)
         self.assertRegex(output, 'inet6 2001:db8:0:f101::15/64 scope global')
         self.assertRegex(output, 'inet6 2001:db8:0:f101::16/64 scope global')
@@ -1304,7 +1316,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_operstate('dummy98', 'routable', setup_state='configuring')
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dummy98')
         print(output)
         self.assertRegex(output, 'inet 10.2.3.4/16 brd 10.2.255.255 scope link deprecated dummy98')
         self.assertRegex(output, 'inet6 2001:db8:0:f101::1/64 scope global')
@@ -1315,7 +1327,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('test1')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'test1'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'test1')
         print(output)
         self.assertRegex(output, '192.168.0.15')
         self.assertRegex(output, '192.168.0.1')
@@ -1328,7 +1340,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('test1')
 
-        output = subprocess.check_output(['ip', 'rule'], universal_newlines=True).rstrip()
+        output = check_output('ip rule')
         print(output)
         self.assertRegex(output, '111')
         self.assertRegex(output, 'from 192.168.100.18')
@@ -1348,11 +1360,11 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
             self.check_link_exists('test1')
             self.check_link_exists('dummy98')
 
-            output = subprocess.check_output(['ip', 'rule', 'list', 'table', '7'], universal_newlines=True).rstrip()
+            output = check_output('ip rule list table 7')
             print(output)
             self.assertRegex(output, '111:     from 192.168.100.18 tos (?:0x08|throughput) iif test1 oif test1 lookup 7')
 
-            output = subprocess.check_output(['ip', 'rule', 'list', 'table', '8'], universal_newlines=True).rstrip()
+            output = check_output('ip rule list table 8')
             print(output)
             self.assertRegex(output, '112:     from 192.168.101.18 tos (?:0x08|throughput) iif dummy98 oif dummy98 lookup 8')
 
@@ -1364,7 +1376,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('test1')
 
-        output = subprocess.check_output(['ip', 'rule'], universal_newlines=True).rstrip()
+        output = check_output('ip rule')
         print(output)
         self.assertRegex(output, '111')
         self.assertRegex(output, 'from 192.168.100.18')
@@ -1381,7 +1393,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('test1')
 
-        output = subprocess.check_output(['ip', 'rule'], universal_newlines=True).rstrip()
+        output = check_output('ip rule')
         print(output)
         self.assertRegex(output, '111')
         self.assertRegex(output, 'not.*?from.*?192.168.100.18')
@@ -1394,15 +1406,15 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.wait_online(['dummy98:routable'])
 
-        output = subprocess.check_output(['ip', '-6', 'route', 'show', 'dev', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 route show dev dummy98')
         print(output)
         self.assertRegex(output, '2001:1234:5:8fff:ff:ff:ff:ff proto static')
         self.assertRegex(output, '2001:1234:5:8f63::1 proto kernel')
 
-        output = subprocess.check_output(['ip', '-6', 'route', 'show', 'dev', 'dummy98', 'default'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 route show dev dummy98 default')
         self.assertRegex(output, 'default via 2001:1234:5:8fff:ff:ff:ff:ff proto static metric 1024 pref medium')
 
-        output = subprocess.check_output(['ip', '-4', 'route', 'show', 'dev', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 route show dev dummy98')
         print(output)
         self.assertRegex(output, '149.10.124.48/28 proto kernel scope link src 149.10.124.58')
         self.assertRegex(output, '149.10.124.64 proto static scope link')
@@ -1410,20 +1422,20 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.assertRegex(output, '192.168.1.1 proto static initcwnd 20')
         self.assertRegex(output, '192.168.1.2 proto static initrwnd 30')
 
-        output = subprocess.check_output(['ip', '-4', 'route', 'show', 'dev', 'dummy98', 'default'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 route show dev dummy98 default')
         self.assertRegex(output, 'default via 149.10.125.65 proto static onlink')
         self.assertRegex(output, 'default via 149.10.124.64 proto static')
         self.assertRegex(output, 'default proto static')
 
-        output = subprocess.check_output(['ip', 'route', 'show', 'type', 'blackhole'], universal_newlines=True).rstrip()
+        output = check_output('ip route show type blackhole')
         print(output)
         self.assertRegex(output, 'blackhole 202.54.1.2 proto static')
 
-        output = subprocess.check_output(['ip', 'route', 'show', 'type', 'unreachable'], universal_newlines=True).rstrip()
+        output = check_output('ip route show type unreachable')
         print(output)
         self.assertRegex(output, 'unreachable 202.54.1.3 proto static')
 
-        output = subprocess.check_output(['ip', 'route', 'show', 'type', 'prohibit'], universal_newlines=True).rstrip()
+        output = check_output('ip route show type prohibit')
         print(output)
         self.assertRegex(output, 'prohibit 202.54.1.4 proto static')
 
@@ -1437,7 +1449,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.check_link_exists('dummy98')
         self.check_link_exists('bond199')
 
-        output = subprocess.check_output(['ip', '-6', 'route', 'list', 'dev', 'bond199'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 route list dev bond199')
         print(output)
         self.assertRegex(output, 'abcd::/16')
         self.assertRegex(output, 'src')
@@ -1449,7 +1461,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('dummy98')
 
-        output = subprocess.check_output(['ip', 'link', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip link show dummy98')
         print(output)
         self.assertRegex(output, '00:01:02:aa:bb:cc')
 
@@ -1459,7 +1471,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('dummy98')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'dummy98'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'dummy98')
         print(output)
         self.assertRegex(output, 'unmanaged')
 
@@ -1469,7 +1481,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('dummy98')
 
-        output = subprocess.check_output(['ip', 'addrlabel', 'list'], universal_newlines=True).rstrip()
+        output = check_output('ip addrlabel list')
         print(output)
         self.assertRegex(output, '2004:da8:1::/64')
 
@@ -1479,7 +1491,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.check_link_exists('dummy98')
 
-        output = subprocess.check_output(['ip', 'neigh', 'list'], universal_newlines=True).rstrip()
+        output = check_output('ip neigh list')
         print(output)
         self.assertRegex(output, '192.168.10.1.*00:00:5e:00:02:65.*PERMANENT')
         self.assertRegex(output, '2004:da8:1::1.*00:00:5e:00:02:66.*PERMANENT')
@@ -1493,12 +1505,12 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.check_link_exists('test1')
         self.check_link_exists('dummy98')
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev test1')
         print(output)
         self.assertRegex(output, 'inet .* scope link')
         self.assertRegex(output, 'inet6 .* scope link')
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev dummy98')
         print(output)
         self.assertNotRegex(output, 'inet6* .* scope link')
 
@@ -1561,10 +1573,10 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['dummy98:routable'])
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dummy98')
         print(output)
         self.assertRegex(output, 'inet 10.2.3.4/16 brd 10.2.255.255 scope global dummy98')
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dummy98')
         print(output)
         self.assertEqual(output, '')
         self.check_operstate('dummy98', 'routable')
@@ -1578,10 +1590,10 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['dummy98:routable'])
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dummy98')
         print(output)
         self.assertRegex(output, 'inet 10.2.3.4/16 brd 10.2.255.255 scope global dummy98')
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dummy98')
         print(output)
         self.assertRegex(output, 'inet6 .* scope link')
         self.check_operstate('dummy98', 'routable')
@@ -1595,7 +1607,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.assertEqual(subprocess.call(['ip', 'link', 'add', 'dummy98', 'type', 'dummy']), 0)
         self.assertEqual(subprocess.call(['ip', 'link', 'set', 'dummy98', 'up']), 0)
         time.sleep(2)
-        output = subprocess.check_output(['ip', 'address', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show test1')
         print(output)
         self.assertRegex(output, 'UP,LOWER_UP')
         self.assertRegex(output, 'inet 192.168.10.30/24 brd 192.168.10.255 scope global test1')
@@ -1604,7 +1616,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.assertEqual(subprocess.call(['ip', 'link', 'add', 'dummy99', 'type', 'dummy']), 0)
         self.assertEqual(subprocess.call(['ip', 'link', 'set', 'dummy99', 'up']), 0)
         time.sleep(2)
-        output = subprocess.check_output(['ip', 'address', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show test1')
         print(output)
         self.assertRegex(output, 'UP,LOWER_UP')
         self.assertRegex(output, 'inet 192.168.10.30/24 brd 192.168.10.255 scope global test1')
@@ -1612,7 +1624,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.assertEqual(subprocess.call(['ip', 'link', 'del', 'dummy98']), 0)
         time.sleep(2)
-        output = subprocess.check_output(['ip', 'address', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show test1')
         print(output)
         self.assertRegex(output, 'UP,LOWER_UP')
         self.assertRegex(output, 'inet 192.168.10.30/24 brd 192.168.10.255 scope global test1')
@@ -1620,7 +1632,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
 
         self.assertEqual(subprocess.call(['ip', 'link', 'del', 'dummy99']), 0)
         time.sleep(2)
-        output = subprocess.check_output(['ip', 'address', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show test1')
         print(output)
         self.assertNotRegex(output, 'UP,LOWER_UP')
         self.assertRegex(output, 'DOWN')
@@ -1630,7 +1642,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.assertEqual(subprocess.call(['ip', 'link', 'add', 'dummy98', 'type', 'dummy']), 0)
         self.assertEqual(subprocess.call(['ip', 'link', 'set', 'dummy98', 'up']), 0)
         time.sleep(2)
-        output = subprocess.check_output(['ip', 'address', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip address show test1')
         print(output)
         self.assertRegex(output, 'UP,LOWER_UP')
         self.assertRegex(output, 'inet 192.168.10.30/24 brd 192.168.10.255 scope global test1')
@@ -1641,7 +1653,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['dummy98:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'dummy98'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'dummy98', env=env)
         print(output)
         self.assertRegex(output, 'Address: 192.168.42.100')
         self.assertRegex(output, 'DNS: 192.168.42.1')
@@ -1680,7 +1692,7 @@ class NetworkdBondTests(unittest.TestCase, Utilities):
         self.check_link_exists('dummy98')
         self.check_link_exists('bond199')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'bond199'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show bond199')
         print(output)
         self.assertRegex(output, 'active_slave dummy98')
 
@@ -1691,7 +1703,7 @@ class NetworkdBondTests(unittest.TestCase, Utilities):
         self.check_link_exists('test1')
         self.check_link_exists('bond199')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'bond199'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show bond199')
         print(output)
         self.assertRegex(output, 'primary test1')
 
@@ -1704,15 +1716,15 @@ class NetworkdBondTests(unittest.TestCase, Utilities):
         self.check_link_exists('dummy98')
         self.check_link_exists('test1')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show dummy98')
         print(output)
         self.assertRegex(output, 'SLAVE,UP,LOWER_UP')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show test1')
         print(output)
         self.assertRegex(output, 'SLAVE,UP,LOWER_UP')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'bond99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show bond99')
         print(output)
         self.assertRegex(output, 'MASTER,UP,LOWER_UP')
 
@@ -1744,7 +1756,7 @@ class NetworkdBondTests(unittest.TestCase, Utilities):
         for trial in range(30):
             if trial > 0:
                 time.sleep(1)
-            output = subprocess.check_output(['ip', 'address', 'show', 'bond99'], universal_newlines=True).rstrip()
+            output = check_output('ip address show bond99')
             print(output)
             if self.get_operstate('bond99') == 'no-carrier':
                 break
@@ -1785,21 +1797,21 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
         self.check_link_exists('test1')
         self.check_link_exists('bridge99')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'test1'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show test1')
         print(output)
         self.assertRegex(output, 'master')
         self.assertRegex(output, 'bridge')
 
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show dummy98')
         print(output)
         self.assertRegex(output, 'master')
         self.assertRegex(output, 'bridge')
 
-        output = subprocess.check_output(['ip', 'addr', 'show', 'bridge99'], universal_newlines=True).rstrip()
+        output = check_output('ip addr show bridge99')
         print(output)
         self.assertRegex(output, '192.168.0.15/24')
 
-        output = subprocess.check_output(['bridge', '-d', 'link', 'show', 'dummy98'], universal_newlines=True).rstrip()
+        output = check_output('bridge -d link show dummy98')
         print(output)
         self.assertEqual(self.read_bridge_port_attr('bridge99', 'dummy98', 'hairpin_mode'), '1')
         self.assertEqual(self.read_bridge_port_attr('bridge99', 'dummy98', 'path_cost'), '400')
@@ -1818,16 +1830,16 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
         self.check_operstate('dummy98', 'enslaved')
         self.check_operstate('bridge99', 'routable')
 
-        self.assertEqual(subprocess.call(['ip', 'address', 'add', '192.168.0.16/24', 'dev', 'bridge99']), 0)
+        check_output('ip address add 192.168.0.16/24 dev bridge99')
         time.sleep(1)
 
-        output = subprocess.check_output(['ip', 'addr', 'show', 'bridge99'], universal_newlines=True).rstrip()
+        output = check_output('ip addr show bridge99')
         print(output)
         self.assertRegex(output, '192.168.0.16/24')
 
         self.check_operstate('bridge99', 'routable')
 
-        self.assertEqual(subprocess.call(['ip', 'link', 'del', 'test1']), 0)
+        self.assertEqual(call('ip link del test1'), 0)
         time.sleep(3)
 
         self.check_operstate('bridge99', 'degraded-carrier')
@@ -1837,7 +1849,7 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
 
         self.check_operstate('bridge99', 'no-carrier')
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'bridge99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show bridge99')
         print(output)
         self.assertRegex(output, 'NO-CARRIER')
         self.assertNotRegex(output, '192.168.0.15/24')
@@ -1847,8 +1859,7 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
         self.copy_unit_to_networkd_unit_path('11-dummy.netdev', '12-dummy.netdev', '26-bridge.netdev',
                                              '26-bridge-slave-interface-1.network', '26-bridge-slave-interface-2.network',
                                              'bridge99-ignore-carrier-loss.network')
-
-        subprocess.call(['ip', 'rule', 'del', 'table', '100'])
+        call('ip rule del table 100')
 
         self.start_networkd()
 
@@ -1856,26 +1867,26 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
         self.check_link_exists('test1')
         self.check_link_exists('bridge99')
 
-        self.assertEqual(subprocess.call(['ip', 'address', 'add', '192.168.0.16/24', 'dev', 'bridge99']), 0)
+        check_output('ip address add 192.168.0.16/24 dev bridge99')
         time.sleep(1)
 
-        self.assertEqual(subprocess.call(['ip', 'link', 'del', 'test1']), 0)
-        self.assertEqual(subprocess.call(['ip', 'link', 'del', 'dummy98']), 0)
+        check_output('ip link del test1')
+        check_output('ip link del dummy98')
         time.sleep(3)
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'bridge99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show bridge99')
         print(output)
         self.assertRegex(output, 'NO-CARRIER')
         self.assertRegex(output, 'inet 192.168.0.15/24 brd 192.168.0.255 scope global bridge99')
         self.assertRegex(output, 'inet 192.168.0.16/24 scope global secondary bridge99')
 
-        subprocess.call(['ip', 'rule', 'del', 'table', '100'])
+        call('ip rule del table 100')
 
     def test_bridge_ignore_carrier_loss_frequent_loss_and_gain(self):
         self.copy_unit_to_networkd_unit_path('26-bridge.netdev', '26-bridge-slave-interface-1.network',
                                              'bridge99-ignore-carrier-loss.network')
 
-        subprocess.call(['ip', 'rule', 'del', 'table', '100'])
+        call('ip rule del table 100')
 
         self.start_networkd()
 
@@ -1904,15 +1915,15 @@ class NetworkdBridgeTests(unittest.TestCase, Utilities):
         else:
             self.assertTrue(False)
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'bridge99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show bridge99')
         print(output)
         self.assertRegex(output, 'inet 192.168.0.15/24 brd 192.168.0.255 scope global bridge99')
 
-        output = subprocess.check_output(['ip', 'rule', 'list', 'table', '100'], universal_newlines=True).rstrip()
+        output = check_output('ip rule list table 100')
         print(output)
         self.assertEqual(output, '0:   from all to 8.8.8.8 lookup 100')
 
-        subprocess.call(['ip', 'rule', 'del', 'table', '100'])
+        call('ip rule del table 100')
 
 class NetworkdLLDPTests(unittest.TestCase, Utilities):
     links = ['veth99']
@@ -1934,7 +1945,7 @@ class NetworkdLLDPTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['veth99:degraded', 'veth-peer:degraded'])
 
-        output = subprocess.check_output(networkctl_cmd + ['lldp'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'lldp', env=env)
         print(output)
         self.assertRegex(output, 'veth-peer')
         self.assertRegex(output, 'veth99')
@@ -1960,7 +1971,7 @@ class NetworkdRATests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['veth99:routable', 'veth-peer:degraded'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '2002:da8:1:0')
 
@@ -1987,7 +1998,7 @@ class NetworkdDHCPServerTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '192.168.5.*')
         self.assertRegex(output, 'Gateway: 192.168.5.1')
@@ -2000,7 +2011,7 @@ class NetworkdDHCPServerTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, 'Gateway: 192.168.5.*')
         self.assertRegex(output, '192.168.5.*')
@@ -2053,13 +2064,13 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '2600::')
         self.assertNotRegex(output, '192.168.5')
 
         # Confirm that ipv6 token is not set in the kernel
-        output = subprocess.check_output(['ip', 'token', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip token show dev veth99')
         print(output)
         self.assertRegex(output, 'token :: dev veth99')
 
@@ -2071,7 +2082,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertNotRegex(output, '2600::')
         self.assertRegex(output, '192.168.5')
@@ -2088,7 +2099,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.wait_address('veth99', r'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic', ipv='-4')
         self.wait_address('veth99', r'inet6 2600::[0-9a-f]*/128 scope global (?:dynamic noprefixroute|noprefixroute dynamic)', ipv='-6')
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '2600::')
         self.assertRegex(output, '192.168.5')
@@ -2102,7 +2113,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
         print('## ip address show dev veth99')
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
         self.assertRegex(output, '12:34:56:78:9a:bc')
         self.assertRegex(output, '192.168.5')
@@ -2110,12 +2121,12 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
 
         # issue #8726
         print('## ip route show table main dev veth99')
-        output = subprocess.check_output(['ip', 'route', 'show', 'table', 'main', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip route show table main dev veth99')
         print(output)
         self.assertNotRegex(output, 'proto dhcp')
 
         print('## ip route show table 211 dev veth99')
-        output = subprocess.check_output(['ip', 'route', 'show', 'table', '211', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip route show table 211 dev veth99')
         print(output)
         self.assertRegex(output, 'default via 192.168.5.1 proto dhcp')
         self.assertRegex(output, '192.168.5.0/24 via 192.168.5.5 proto dhcp')
@@ -2134,7 +2145,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
         self.assertRegex(output, '12:34:56:78:9a:bc')
         self.assertTrue(self.search_words_in_dnsmasq_log('14:rapid-commit', True))
@@ -2146,7 +2157,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
         self.assertRegex(output, '12:34:56:78:9a:bc')
         self.assertFalse(self.search_words_in_dnsmasq_log('14:rapid-commit', True))
@@ -2173,7 +2184,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.wait_address('veth99', r'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic', ipv='-4')
         self.wait_address('veth99', r'inet6 2600::[0-9a-f]*/128 scope global (?:dynamic noprefixroute|noprefixroute dynamic)', ipv='-6')
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99')
         print(output)
         self.assertRegex(output, '192.168.5.* dynamic')
 
@@ -2184,7 +2195,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'route', 'show', 'table', '12'], universal_newlines=True).rstrip()
+        output = check_output('ip route show table 12')
         print(output)
         self.assertRegex(output, 'veth99 proto dhcp')
         self.assertRegex(output, '192.168.5.1')
@@ -2196,7 +2207,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'route', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip route show dev veth99')
         print(output)
         self.assertRegex(output, 'metric 24')
 
@@ -2207,7 +2218,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '192.168.5.*')
 
@@ -2217,7 +2228,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         # Sleep for 120 sec as the dnsmasq minimum lease time can only be set to 120
         time.sleep(125)
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '192.168.5.*')
 
@@ -2232,7 +2243,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.wait_address('veth99', r'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic', ipv='-4')
         self.wait_address('veth99', r'inet6 2600::[0-9a-f]*/128 scope global (?:dynamic noprefixroute|noprefixroute dynamic)', ipv='-6')
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99', 'scope', 'global'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99 scope global')
         print(output)
         self.assertRegex(output, '192.168.5')
         self.assertRegex(output, '2600::')
@@ -2252,12 +2263,12 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_networkd(5)
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global')
         print(output)
         self.assertRegex(output, '192.168.5')
         self.assertRegex(output, 'valid_lft forever preferred_lft forever')
 
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'global'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope global')
         print(output)
         self.assertRegex(output, '2600::')
         self.assertRegex(output, 'valid_lft forever preferred_lft forever')
@@ -2276,12 +2287,12 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.wait_address('veth99', r'inet6 2600::[0-9a-f]*/128 scope global (?:dynamic noprefixroute|noprefixroute dynamic)', ipv='-6')
 
         print('## ip -d link show dev vrf99')
-        output = subprocess.check_output(['ip', '-d', 'link', 'show', 'dev', 'vrf99'], universal_newlines=True).rstrip()
+        output = check_output('ip -d link show dev vrf99')
         print(output)
         self.assertRegex(output, 'vrf table 42')
 
         print('## ip address show vrf vrf99')
-        output = subprocess.check_output(['ip', 'address', 'show', 'vrf', 'vrf99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show vrf vrf99')
         print(output)
         self.assertRegex(output, 'inet 169.254.[0-9]*.[0-9]*/16 brd 169.254.255.255 scope link veth99')
         self.assertRegex(output, 'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
@@ -2289,7 +2300,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.assertRegex(output, 'inet6 .* scope link')
 
         print('## ip address show dev veth99')
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
         self.assertRegex(output, 'inet 169.254.[0-9]*.[0-9]*/16 brd 169.254.255.255 scope link veth99')
         self.assertRegex(output, 'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
@@ -2297,7 +2308,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.assertRegex(output, 'inet6 .* scope link')
 
         print('## ip route show vrf vrf99')
-        output = subprocess.check_output(['ip', 'route', 'show', 'vrf', 'vrf99'], universal_newlines=True).rstrip()
+        output = check_output('ip route show vrf vrf99')
         print(output)
         self.assertRegex(output, 'default via 192.168.5.1 dev veth99 proto dhcp src 192.168.5.')
         self.assertRegex(output, 'default dev veth99 proto static scope link')
@@ -2307,7 +2318,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.assertRegex(output, '192.168.5.1 dev veth99 proto dhcp scope link src 192.168.5')
 
         print('## ip route show table main dev veth99')
-        output = subprocess.check_output(['ip', 'route', 'show', 'table', 'main', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip route show table main dev veth99')
         print(output)
         self.assertEqual(output, '')
 
@@ -2322,14 +2333,14 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq()
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(networkctl_cmd + ['status', 'veth99'], universal_newlines=True, env=env).rstrip()
+        output = check_output(*networkctl_cmd, 'status', 'veth99', env=env)
         print(output)
         self.assertRegex(output, '192.168.5')
 
-        output = subprocess.check_output(['ip', 'route', 'list', 'dev', 'veth99', '10.0.0.0/8'], universal_newlines=True).rstrip()
+        output = check_output('ip route list dev veth99 10.0.0.0/8')
         print(output)
         self.assertRegex(output, 'onlink')
-        output = subprocess.check_output(['ip', 'route', 'list', 'dev', 'veth99', '192.168.100.0/24'], universal_newlines=True).rstrip()
+        output = check_output('ip route list dev veth99 192.168.100.0/24')
         print(output)
         self.assertRegex(output, 'onlink')
 
@@ -2341,31 +2352,31 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_dnsmasq(lease_time='2m')
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
 
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope global dynamic')
         self.assertNotRegex(output, 'inet6 2600::[0-9a-f]*/128 scope global dynamic')
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope link')
         self.assertRegex(output, 'inet6 .* scope link')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global dynamic')
         self.assertRegex(output, 'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope link')
         self.assertNotRegex(output, 'inet .* scope link')
 
         print('Wait for the dynamic address to be expired')
         time.sleep(130)
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
 
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope global dynamic')
         self.assertNotRegex(output, 'inet6 2600::[0-9a-f]*/128 scope global dynamic')
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope link')
         self.assertRegex(output, 'inet6 .* scope link')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global dynamic')
         self.assertRegex(output, 'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope link')
         self.assertNotRegex(output, 'inet .* scope link')
 
         self.search_words_in_dnsmasq_log('DHCPOFFER', show_all=True)
@@ -2376,16 +2387,16 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         self.start_networkd(0)
         self.wait_online(['veth99:degraded', 'veth-peer:routable'])
 
-        output = subprocess.check_output(['ip', 'address', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip address show dev veth99')
         print(output)
 
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope global dynamic')
         self.assertNotRegex(output, 'inet6 2600::[0-9a-f]*/128 scope global dynamic')
-        output = subprocess.check_output(['ip', '-6', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -6 address show dev veth99 scope link')
         self.assertRegex(output, 'inet6 .* scope link')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global dynamic')
         self.assertNotRegex(output, 'inet 192.168.5.[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'link'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope link')
         self.assertRegex(output, 'inet .* scope link')
 
     def test_dhcp_client_route_remove_on_renew(self):
@@ -2398,7 +2409,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
 
         # test for issue #12490
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global dynamic')
         print(output)
         self.assertRegex(output, 'inet 192.168.5.1[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
         address1=None
@@ -2407,7 +2418,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
                 address1 = line.split()[1].split('/')[0]
                 break
 
-        output = subprocess.check_output(['ip', '-4', 'route', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 route show dev veth99')
         print(output)
         self.assertRegex(output, f'default via 192.168.5.1 proto dhcp src {address1} metric 1024')
         self.assertRegex(output, f'192.168.5.1 proto dhcp scope link src {address1} metric 1024')
@@ -2418,7 +2429,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         print('Wait for the dynamic address to be expired')
         time.sleep(130)
 
-        output = subprocess.check_output(['ip', '-4', 'address', 'show', 'dev', 'veth99', 'scope', 'global', 'dynamic'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 address show dev veth99 scope global dynamic')
         print(output)
         self.assertRegex(output, 'inet 192.168.5.2[0-9]*/24 brd 192.168.5.255 scope global dynamic veth99')
         address2=None
@@ -2429,7 +2440,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
 
         self.assertNotEqual(address1, address2)
 
-        output = subprocess.check_output(['ip', '-4', 'route', 'show', 'dev', 'veth99'], universal_newlines=True).rstrip()
+        output = check_output('ip -4 route show dev veth99')
         print(output)
         self.assertNotRegex(output, f'default via 192.168.5.1 proto dhcp src {address1} metric 1024')
         self.assertNotRegex(output, f'192.168.5.1 proto dhcp scope link src {address1} metric 1024')