[Unit]
Description=Backup ~/.mozilla/firefox/<profile> directory
ConditionFileIsExecutable=/usr/lib/systemd/scripts/backup-firefox
ConditionKernelCommandLine=!systemd.setenv=REALTIME=true

[Service]
EnvironmentFile=/etc/backup-settings
Nice=19
IOSchedulingClass=2
IOSchedulingPriority=7
ExecStart=/usr/lib/systemd/scripts/backup-firefox