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https://github.com/Mic92/envfs
Fuse filesystem that returns symlinks to executables based on the PATH of the requesting process.
https://github.com/Mic92/envfs
build-with-buildbot
Last synced: 23 days ago
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Fuse filesystem that returns symlinks to executables based on the PATH of the requesting process.
- Host: GitHub
- URL: https://github.com/Mic92/envfs
- Owner: Mic92
- Created: 2021-01-02T16:24:46.000Z (about 4 years ago)
- Default Branch: main
- Last Pushed: 2024-10-22T09:08:24.000Z (3 months ago)
- Last Synced: 2024-10-23T13:41:56.989Z (2 months ago)
- Topics: build-with-buildbot
- Language: Rust
- Homepage:
- Size: 1.31 MB
- Stars: 239
- Watchers: 10
- Forks: 5
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
- awesome-starred - Mic92/envfs - Fuse filesystem that returns symlinks to executables based on the PATH of the requesting process. (Rust)
- awesome-starred - Mic92/envfs - Fuse filesystem that returns symlinks to executables based on the PATH of the requesting process. (Rust)
README
# Envfs
A fuse filesystem that dynamically populates contents of /bin and /usr/bin/ so
that it contains all executables from the PATH of the requesting process. This
allows executing FHS based programs on a non-FHS system. For example, this is
useful to execute shebangs on NixOS that assume hard coded locations like /bin
or /usr/bin etc.
## Demo
Mount envfs on /usr/bin `sudo envfs /usr/bin`
Programs are magically available, based on the PATH of the calling process.
`$ /usr/bin/env --version`
```
env (GNU coreutils) 9.1
Packaged by https://nixos.org
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later .
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Richard Mlynarik, David MacKenzie, and Assaf Gordon.
```
`$ echo $PATH`
If the caller doesn't have the binary in the PATH, it will fail.
`$ PATH= /usr/bin/env --version 2>&1 || true`
As you can see, /usr/bin is empty. `$ ls -la /usr/bin`
```
total 1
drwxr-xr-x 3345300086 root root 0 Jan 1 1970 .
drwxr-xr-x 3 root root 3 Sep 5 13:04 ..
```
By default, binaries are only available whenever the calling process executes or
open a program, not when using stat or listing the directory:
`$ ls -la /usr/bin/env 2>&1 || true`
```
ls: cannot access '/usr/bin/env': No such file or directory
```
This behaviour can be overridden by setting `ENVFS_RESOLVE_ALWAYS=1`.
`$ ENVFS_RESOLVE_ALWAYS=1 ls -la /usr/bin/env`
```
lr----x--t 1 root root 0 Jan 1 1970 /usr/bin/env -> /nix/store/4vjigg3pr8bns6id4af51mza5p73l9lx-coreutils-9.1/bin/env
```
In conclusion, combined with the usual Nix wrappers or nix-shells, it makes
things magically work!
## Installation in NixOS
Choose one of the following methods:
### In NixOS starting with 23.05 (Current recommendation)
Since NixOS 23.05 you can enable envfs with a single line:
```nix
{
services.envfs.enable = true;
}
```
### Flakes
If you use nix flakes support:
```nix
{
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
];
};
};
}
```
### [niv](https://github.com/nmattia/niv)
First add it to niv:
```console
$ niv add Mic92/envfs
```
Then add the following to your configuration.nix in the `imports` list:
```nix
{
imports = [ "${(import ./nix/sources.nix).envfs}/modules/envfs.nix" ];
}
```
### nix-channel
As root run:
```console
$ 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:
```nix
{
imports = [ ];
}
```
### fetchTarball
Add the following to your configuration.nix:
```nix
{
imports = [ "${builtins.fetchTarball "https://github.com/Mic92/envfs/archive/main.tar.gz"}/modules/envfs.nix" ];
}
```
or with pinning:
```nix
{
imports = let
# replace this with an actual commit id or tag
commit = "f2783a8ef91624b375a3cf665c3af4ac60b7c278";
in [
"${builtins.fetchTarball {
url = "https://github.com/Mic92/envfs/archive/${commit}.tar.gz";
# replace this with an actual hash
sha256 = "0000000000000000000000000000000000000000000000000000";
}}/modules/envfs.nix"
];
}
```
## Build and run from source
```console
$ nix-build
$ sudo ./result/bin/envfs -o bind-mount=/bin /usr/bin
```