Difference systemd executable command methods

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1

What is the difference between systemd.services.<name>.script and systemd.services.<name>.serviceConfig.ExecStart?

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2

ExecStart does not run in a shell, script runs in a shell.

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3

what does that mean? I can use ExecStart to execute the command node index.js, but I can also use script to execute the command node index.js. So I do not really understand when to use what.

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4

Compare ExecStart = "a && b";, script = "a && b";, the former won’t work, the latter will.

script just boils down to a ExecStart call with a generated script on the fly with a runtime shell.

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5

To expand on that:
ExecStart is the normal systemd attribute, nothing fancy.
script is just a convince wrapper that writes the content to a text file, makes it executable and adds that path to ExecStart, so that services can easily run a shell command or two when starting the service without having to worry aout that.

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6

Oh okay, so I can basically just always use script instead of ExecStart? Is there also something like this wrapper for ExecPreStart?

7

Basically yes but if you don’t need shell features then the plain command should be used. Basically avoid the extra abstraction step if possible.

no

8

Actually yes. In fact, there’s one for all the Exec things.

  • ExecStart: script
  • ExecStartPre: preStart
  • ExecStartPost: postStart
  • ExecStop: preStop
  • ExecStopPost: postStop
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9

I was searching for more variants if script but couldn’t immediately find it because of the naming.

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