systemd-logind to be safe. See
https://cgit.freedesktop.org/xorg/xserver/commit/?id=dc48bd653c7e101.)
- * All kernel install plugins are called with the environment variable
+ * All kernel-install plugins are called with the environment variable
KERNEL_INSTALL_MACHINE_ID which is set to the machine ID given by
- /etc/machine-id. If the file is missing or empty, the variable is
- empty and BOOT_DIR_ABS is the path of a temporary directory which is
- removed after all the plugins exit. So, if KERNEL_INSTALL_MACHINE_ID
- is empty, all plugins should not put anything in BOOT_DIR_ABS.
+ /etc/machine-id. If the machine ID could not be determined,
+ $KERNEL_INSTALL_MACHINE_ID will be empty. Plugins should not put
+ anything in the entry directory (passed as the second argument) if
+ $KERNEL_INSTALL_MACHINE_ID is empty. For backwards compatiblity, a
+ temporary directory is passed as the entry directory and removed
+ after all the plugins exit.
Contributions from: Adrian Heine né Lang, Aggelos Avgerinos, Alexander
Kurtz, Alexandros Frantzis, Alexey Brodkin, Alex Lu, Amir Pakdel, Amir