Envfs
Fuse filesystem that returns symlinks to executables based on the PATH of the requesting process. This is useful to execute shebangs on NixOS that assume hard coded locations in locations like /bin or /usr/bin etc.
Demo
$ ls -l /usr/bin/{bash,python}
lr----x--t 0 root 1 Jan 1970 /usr/bin/bash -> /nix/store/j37555sj2w3xsql3f8qrwbaim7pv67hg-bash-interactive-4.4-p23/bin/bash
lr----x--t 0 root 1 Jan 1970 /usr/bin/python -> /home/joerg/.nix-profile/bin/python
$ cat > foo.py <<EOF
#!/usr/bin/python
print("hello world")
EOF
$ chmod +x ./foo.py
$ ./foo.py
hello world
Installation in NixOS
Choose one of the following methods:
niv (Current recommendation)
First add it to niv:
$ niv add Mic92/envfs
Then add the following to your configuration.nix in the imports list:
{
imports = [ "${(import ./nix/sources.nix).envfs}/modules/envfs.nix" ];
}
nix-channel
As root run:
$ nix-channel --add https://github.com/Mic92/envfs/archive/main.tar.gz envfs
$ nix-channel --update
Then add the following to your configuration.nix in the imports list:
{
imports = [ <envfs/modules/envfs.nix> ];
}
fetchTarball
Add the following to your configuration.nix:
{
imports = [ "${builtins.fetchTarball "https://github.com/Mic92/envfs/archive/main.tar.gz"}/modules/envfs.nix" ];
}
or with pinning:
{
imports = let
# replace this with an actual commit id or tag
commit = "f2783a8ef91624b375a3cf665c3af4ac60b7c278";
in [
"${builtins.fetchTarball {
url = "https://github.com/Mic92/envfs/archive/${commit}.tar.gz";
# replace this with an actual hash
sha256 = "0000000000000000000000000000000000000000000000000000";
}}/modules/envfs.nix"
];
}
Flakes
If you use experimental nix flakes support:
{
inputs.envfs.url = "github:Mic92/envfs";
inputs.envfs.inputs.nixpkgs.follows = "nixpkgs";
outputs = { self, nixpkgs, envfs }: {
# change `yourhostname` to your actual hostname
nixosConfigurations.yourhostname = nixpkgs.lib.nixosSystem {
# change to your system:
system = "x86_64-linux";
modules = [
./configuration.nix
envfs.nixosModules.envfs
];
};
};
}
Build and run from source
$ nix-build
$ sudo ./result/bin/envfs /usr/bin
$ mount --bind /usr/bin /bin
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