title: systemd: "Environment" directive to set PATH
body: <p>What is the right way to set PATH variable in a <code>systemd</code> unit file?
  After seeing a few examples, I tried to use the format below, but the variable doesn't seem to expand.</p>
  
  <pre><code>Environment="PATH=/local/bin:$PATH"
  </code></pre>
  
  <p>I am trying this on CoreOS with the below version of systemd.</p>
  
  <pre><code>systemd 225
  -PAM +AUDIT +SELINUX +IMA -APPARMOR +SMACK -SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT -GNUTLS -ACL +XZ -LZ4 +SECCOMP +BLKID -ELFUTILS +KMOD -IDN
  </code></pre>