[systemd-devel] Antw: [EXT] A sh -c '${name} and $name' are treated inconsistently within a .service unit

[Ulrich Windl]

>>> <u34 at net9.ga> schrieb am 27.08.2020 um 18:11 in Nachricht
<E1kBKUz-00084B-U2 at mx1.net9.ga>:
> Consider 
> 
> [Unit]
> Description=Is it looking for ${} construct in the wrong place?
> [Service]
> Type=oneshot
> ExecStart=/bin/bash ‑c 'set ‑x; declare ‑r str="1 2"; echo ${str}; echo
$str; 

It seems systemd substitutes ${str} before the command is executed. See
systemd.service(5):

       Basic environment variable substitution is supported. Use "${FOO}" as
       part of a word, or as a word of its own, on the command line, in which
       case it will be replaced by the value of the environment variable
       including all whitespace it contains, resulting in a single argument.


Did you try to "escape" the "{" and "}"?

> exit 0;'
> 
> When ran, the journal has:
> 
> bash[14190]: + declare ‑r 'str=1 2'
> bash[14190]: + echo
> bash[14190]: + echo 1 2
> bash[14190]: 1 2
> bash[14190]: + exit 0
> 
> Note the top bash[14190]: + echo line. It has no arguments. Since the other

> echo line
> has its 1 2 arguments, I find this behaviour inconsistent. And surprising. 
> As such, I
> think this is a bug.
> It could be that the ${NAME} construct is looked for in the environment. But

> then, why 
> $NAME works in the script, but not ${NAME}?
> 
> In addition, for the top bash[14190]: + echo line, isn't there a missing 
> empty, just
> [bash[14190]:, line?
> 
> Same results were obtained with systemd 241‑7 and 246.2.
> 
> u34.
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