(environment-variables)=
# Environment variables

SHOP requires binaries and a license to work properly.
The files can be located in the current working directory or in an other directory.
If the binaries and/or the license file is located in a different directory, you need to inform SHOP where to locate the files.

SHOP contains the following environment variables:

- `SHOP_BINARY_PATH`
- `SHOP_LICENSE_PATH`
- `SHOP_CPLEX_PATH` on Windows
- `SHOP_GUROBI_PATH` on Windows
- [deprecated] `ICC_COMMAND_PATH`

## `SHOP_BINARY_PATH`

The `SHOP_BINARY_PATH` environment variable specifies the path to the core SHOP solver binaries. If not set, SHOP will look for the binaries in `ICC_COMMAND_PATH` (if it exists) and then in the current working directory.

## `SHOP_CPLEX_PATH` and `SHOP_GUROBI_PATH` on Windows

Starting with `SHOP 17.15.0`, these environment variables on Windows specify the paths to the _external optimization solver_ binaries for CPLEX and GUROBI. If not set, SHOP will look for the external binaries in `SHOP_BINARY_PATH` and `ICC_COMMAND_PATH` (if they exist) and then in the current working directory.

## `SHOP_LICENSE_PATH`

The `SHOP_LICENSE_PATH` environment variable specifies the path to the licence file. If not set, SHOP will look for the license in `ICC_COMMAND_PATH` (if it exists) and then in the current working directory.

## [deprecated]: `ICC_COMMAND_PATH`

This is the old path used to show SHOP where to look for the license and binaries, and is deprecated. Use `SHOP_BINARY_PATH`, `SHOP_CPLEX_PATH`/`SHOP_GUROBI_PATH` and `SHOP_LICENSE_PATH` instead.

## SHOP binaries location priority

It is possible to set the required variables both in pyshop and using environment variables.
Environment priority is as follows:

1. If you use pyshop, the inline variables in the `ShopSession` constructor have the highest priority and will ignore environment variables. E.g:

```python
ShopSession(
    license_path="/license/path",
    solver_path ="/solver/path",
    cplex_path  ="/cplex/path", # On Windows
    gurobi_path ="/gurobi/path" # On Windows
)
```

2. Environment variables
3. Current directory