0

This was previously working just fine, but a failed micro-sd card on a Raspberry Pi Zero W forced me to reinstall the system. The old system was running on an older release of the OS, so that could definitely be part of the issue. When I issue the command:

systemctl enable i2cget.service

I get the error:

Failed to enable unit: Cannot alias i2cget.service as i2cget

and no symlink is created.

Oddly enough, when I check the status, it says it is enabled, and when I reboot, the service is live. I don't understand what is going on. Could there be an issue with the fact the symlink does not exist in /etc/systemd/system/multi-user.target.wants?

This us running under Raspbian 1:6.6.51-1+rpt3

/lib/systemd/system/i2cget.service:

[Unit]
Description=get-i2c daemon
After=network.target
Requires=network.target

[Service]
Restart=on-failure
RestartSec=4s
ExecStart=/usr/bin/python3 /home/fpp/media/scripts/get-i2c.py

[Install]
Alias=i2cget
WantedBy=multi-user.target
Improve this question

1 Answer 1

Reset to default
0

You cannot and you don't need to alias xy.service to xy. All systemd tools allow you to use xy without .service by default.

From man systemd.unit:

Aliases obey the following restrictions: a unit of a certain type (".service", ".socket", ...) can only be aliased by a name with the same type suffix.

To get rid of the error, you have to remove the line with Alias or change it to 

Alias=something-different-than-i2cget.service

From man systemctl:

If the suffix is not specified (unit name is "abbreviated"), systemctl will append a suitable suffix, ".service" by default, and a type-specific suffix in case of commands which operate only on specific unit types.

There is no need to alias i2cget.service to i2cget. You can use journalctl -u i2cget or systemctl status i2cget without that alias.

You could change your alias to 

Alias=i.service
and use systemctl status i and journalctl -u i.

Improve this answer
4
  • Perhaps I don't understand what an alias is supposed to do. I have tried several different options such as Alias=geti2c, Alias=i2c-get, and a couple of others. Again, this was working fine in the last release. Commented Jan 2 at 13:39
  • Could it be that you didn't see the warning and it still "works" in the sense that you can use systemctl status i2cget? Commented Jan 3 at 11:09
  • I am afraid I am still not following. What do you mean "did not see the warning"? This has always worked in previous versions with no warning, and it creates the link in previous versions. It still does in previous versions. Even now, it claims to delete the link when I disable the service, even though it does not exist. I will ask again, what is the purpose of an alias? I thought it was to allow the use of some "shortcut" when starting / stopping / inspecting etc. the service. It complains no matter what I try, Commented Jan 11 at 7:06
  • Just use .service for your alias. Commented Jan 14 at 13:05

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.