Short answer:
bad : It shows Systemd Unit files status - you will find this option in system which use
systemd
you can check this option using command:
sudo systemctl is-enabled <unit-name>
if that unit file support native systemd then it will give output enabled , disabled etc. if not support then it will give status with message like.
sudo systemctl is-enabled apache2
apache2.service is not a native service, redirecting to systemd-sysv-install
Executing /lib/systemd/systemd-sysv-install is-enabled apache2
enabled
but with command :
systemctl status apache2
or
service apache2 status
it gives status bad. ( may be it is because not able to print complete message or developer decided to print bad)
Long Answer:
what is system unit files ?
Units are the objects that systemd knows how to manage. These are basically a standardized representation of system resources that can be managed by the suite of daemons and manipulated by the provided utilities. It can be used to abstract services, network resources, devices, filesystem mounts, and isolated resource pools.
You can read in detail about systemd units here and here
example:
systemctl status apache2
* apache2.service - LSB: Apache2 web server
Loaded: loaded (/etc/init.d/apache2; bad; vendor preset: enabled)
Drop-In: /lib/systemd/system/apache2.service.d
`-apache2-systemd.conf
Active: active (running) since Wed 2016-10-12 14:29:42 UTC; 17s ago
Docs: man:systemd-sysv-generator(8)
Process: 1027 ExecStart=/etc/init.d/apache2 start (code=exited, status=0/SUCCESS)
systemctl will check apache2 is native units or not. if not then it
will ask systemd-sysv-generator to generate a file in unit format that support similarly to native units. In above example generated file kept at
/lib/systemd/system/apache2.service.d/apache2-systemd.conf
Drop-In: /lib/systemd/system/apache2.service.d
`-apache2-systemd.conf
Note: you can find generator at /lib/systemd/system-generators/systemd-sysv-generator and you can read more about that
man systemd-sysv-generator
Main point:
is-enabled NAME...
Checks whether any of the specified unit files are enabled (as with
enable). Returns an exit code of 0 if at least one is enabled,
non-zero otherwise. Prints the current enable status (see table).
To suppress this output, use --quiet.
Table 1. is-enabled output
+------------------+-------------------------+-----------+
|Name | Description | Exit Code |
+------------------+-------------------------+-----------+
|"enabled" | Enabled via | |
+------------------+ .wants/, .requires/ | |
|"enabled-runtime" | or alias symlinks | |
| | (permanently in | 0 |
| | /etc/systemd/system/, | |
| | or transiently in | |
| | /run/systemd/system/). | |
+------------------+-------------------------+-----------+
|"linked" | Made available through | |
+------------------+ one or more symlinks | |
|"linked-runtime" | to the unit file | |
| | (permanently in | |
| | /etc/systemd/system/ | |
| | or transiently in | > 0 |
| | /run/systemd/system/), | |
| | even though the unit | |
| | file might reside | |
| | outside of the unit | |
| | file search path. | |
+------------------+-------------------------+-----------+
|"masked" | Completely disabled, | |
+------------------+ so that any start | |
|"masked-runtime" | operation on it fails | |
| | (permanently in | > 0 |
| | /etc/systemd/system/ | |
| | or transiently in | |
| | /run/systemd/systemd/). | |
+------------------+-------------------------+-----------+
|"static" | The unit file is not | 0 |
| | enabled, and has no | |
| | provisions for enabling | |
| | in the "[Install]" | |
| | section. | |
+------------------+-------------------------+-----------+
|"indirect" | The unit file itself is | 0 |
| | not enabled, but it has | |
| | a non-empty Also= | |
| | setting in the | |
| | "[Install]" section, | |
| | listing other unit | |
| | files that might be | |
| | enabled. | |
+------------------+-------------------------+-----------+
|"disabled" | Unit file is not | > 0 |
| | enabled, but contains | |
| | an "[Install]" section | |
| | with installation | |
| | instructions. | |
+------------------+-------------------------+-----------+
|"bad" | Unit file is invalid or | > 0 |
| | another error occurred. | |
| | Note that is-enabled | |
| | will not actually | |
| | return this state, but | |
| | print an error message | |
| | instead. However the | |
| | unit file listing | |
| | printed by | |
| | list-unit-files might | |
| | show it. | |
+------------------+-------------------------+-----------+
if we run command :
sudo systemctl is-enabled ssh
enabled
sudo systemctl is-enabled docker
enabled
sudo systemctl is-enabled apache2
apache2.service is not a native service, redirecting to systemd-sysv-install
Executing /lib/systemd/systemd-sysv-install is-enabled apache2
enabled
you can see if units are native to systemd like ssh and docker in above output it will show only enabled and units that are not support native like apache2 still enabled but giving messages with that but not printing bad here because of this condition:
+------------------+-------------------------+-----------+
|"bad" | Unit file is invalid or | > 0 |
| | another error occurred. | |
| | Note that is-enabled | |
| | will not actually | |
| | return this state, but | |
| | print an error message | |
| | instead. However the | |
| | unit file listing | |
| | printed by | |
| | list-unit-files might | |
| | show it. | |
+------------------+-------------------------+-----------+
Solution:
status bad will not create problem (i am not sure it depends) but it will not provide all functionality of systemctl.
you can wait for next release of that package that will natively support systemd. or you can write unit file for your service or any other resource using given references.
You can read in detail about systemd , systemctl and units using below References :
Systemctl
Systemd units and Here
Systemd
