---
title: Known Environment Variables
+category: Interfaces
---
# Known Environment Variables
* `$SYSTEMD_CRYPTTAB` — if set, use this path instead of /etc/crypttab. Only
useful for debugging. Currently only supported by systemd-cryptsetup-generator.
-* `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in SystemdOptions
- EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
+* `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in the
+ SystemdOptions EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
* `$SYSTEMD_IN_INITRD` — takes a boolean. If set, overrides initrd detection.
This is useful for debugging and testing initrd-only programs in the main