[systemd-devel] Problem expanding environment variables

[Thomas Köller]

I am having problems expanding environment variables in a service file. 
This test serivice illustrates the problem:

root at yoga:/etc/systemd/system# cat varexp.service
[Unit]
Description = Test environment variable expansion

[Service]
Type = oneshot
Environment = "VAR=abc-xyz"
ExecStart = sh -c 'echo Res: ${VAR#abc-}'

Running it yields the following result:

root at yoga:/etc/systemd/system# systemctl status varexp.service
○ varexp.service - Test environment variable expansion
      Loaded: loaded (/etc/systemd/system/varexp.service; static)
     Drop-In: /usr/lib/systemd/system/service.d
              └─10-timeout-abort.conf
      Active: inactive (dead)

Sep 06 10:17:16 yoga systemd[1]: Starting varexp.service - Test 
environment variable expansion...
Sep 06 10:17:16 yoga (sh)[8541]: varexp.service: Invalid environment 
variable name evaluates to an empty string: VAR#abc-
Sep 06 10:17:16 yoga sh[8541]: Res:
Sep 06 10:17:16 yoga systemd[1]: varexp.service: Deactivated successfully.
Sep 06 10:17:16 yoga systemd[1]: Finished varexp.service - Test 
environment variable expansion.

According to the output lines above, it is the shell that complains. 
However, running the command from an interactive shell yields the 
expected result:

root at yoga:/etc/systemd/system# VAR='abc-xyz' sh -c 'echo ${VAR#abc-}'
xyz

What is wrong here?