Change:
When using fcron, the systab gets generated from the system cron commands just like any of the other crons but the logic that updates that in fcron appears to have stopped working in 17.03. Looking in the module I see a commented out line that attempts to do it but when I run it by hand I receive an error about the file not being a regular file. fcron— a system cron entry— ensuring fcrontab is started check systab— the systab loading command in the fcron unit to attempt to install systab errors about not being a regular file Copying the file to another location via cat does make this work correctly so I'm not sure what the solution might be. System: 17.03.1016. (Gorilla) Nix version: nix-env (Nix) 1.11.8 Nixpkgs version: "17.03.1016."
Hmm... I seem to be hitting this very same problem with fcron on (which should include the fixing commit): gives me the following logs: Would anyone have a pointer as to what could be going wrong? I've checked and the in the systemd unit is correctly the wrapped one.
I also noticed fcrontab needs itself in PATH: the following works for me:
I was hitting this issue due to the nix store being auto-optimized and thus using hard links for the systab: fcron refuses to open the file if it has a hard link, apparently for security reasons. (apart from the syntax error that arose during minification of the example, thanks for the feedback!) See for a possible fix :)

Discussion:
<ins> {stdenv, fetchurl, yacc, flex, pkgconfig, glib, xz}: stdenv.mkDerivation rec { version = "0.15.2"; name = "vala-${version}"; src = fetchurl { url = "mirror://gnome/sources/vala/0.15/${name}.tar.xz"; sha256 = "0g71zq6dpqrw2f40wfzdf18fdw41ymr17laqniy2kr622hkxdi8w"; }; buildNativeInputs = [ yacc flex pkgconfig xz ]; buildInputs = [ glib ]; meta = { description = "Compiler for the GObject type system"; homepage = "http://live.gnome.org/Vala"; license = "free-copyleft"; platforms = stdenv.lib.platforms.all; maintainers = [ stdenv.lib.maintainers.antono ]; }; } </ins>

<ins> {stdenv, fetchurl, yacc, flex, pkgconfig, glib, xz}: stdenv.mkDerivation rec { version = "0.16.1"; name = "vala-${version}"; src = fetchurl { url = "mirror://gnome/sources/vala/0.16/${name}.tar.xz"; sha256 = "1n708n9ixyy9qrzyv1wf4ybvcclx43ib9ki028wwpvkz6kv8zqlb"; }; buildNativeInputs = [ yacc flex pkgconfig xz ]; buildInputs = [ glib ]; meta = { description = "Compiler for the GObject type system"; homepage = "http://live.gnome.org/Vala"; license = "free-copyleft"; platforms = stdenv.lib.platforms.all; maintainers = [ stdenv.lib.maintainers.antono ]; }; } </ins>

{stdenv, fetchurl, yacc, flex, pkgconfig, glib, xz}: stdenv.mkDerivation rec { <del> name = "vala-0.14.2"; </del> <ins> version = "0.17.2"; name = "vala-${version}"; </ins> src = fetchurl { <del> url = mirror://gnome/sources/vala/0.14/vala-0.14.2.tar.xz; sha256 = "1l5kllw9vpwv24lzv9fp64l3sad46wpxgvsgryrwlrjg91w6jzl0"; </del> <ins> url = "mirror://gnome/sources/vala/0.17/${name}.tar.xz"; sha256 = "09i2s0dwmrk147ind2dx7nq845g12fp6fsjqrphhrr0dbi0zzgh3"; </ins> }; buildNativeInputs = [ yacc flex pkgconfig xz ];

meta = { description = "Compiler for the GObject type system"; homepage = "http://live.gnome.org/Vala"; <ins> license = "free-copyleft"; platforms = stdenv.lib.platforms.all; maintainers = [ stdenv.lib.maintainers.antono ]; </ins> }; }

urweb = callPackage ../development/compilers/urweb { }; <del> vala = callPackage ../development/compilers/vala { }; </del> <ins> vala = vala17; vala15 = callPackage ../development/compilers/vala/15.2.nix { }; vala16 = callPackage ../development/compilers/vala/16.1.nix { }; vala17 = callPackage ../development/compilers/vala/default.nix { }; </ins> visualcpp = callPackage ../development/compilers/visual-c++ { };