how to correctly set the proxy in `.condarc` file

I am install a private python distribution in julia, but Conda seems to have a proxy error:
```bash
julia>ENV["PYTHON"]=""
julia> build PyCall
julia>
Building PyCall → `~/.julia/scratchspaces/44cfe95a-1eb2-52ea-b672-e2afdf69b78f/62f417f6ad727987c755549e9cd88c46578da562/build.log`
ERROR: Error building `PyCall`:
WARNING: failed to select UTF-8 encoding, using ASCII
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
Collecting package metadata (current_repodata.json): ...working... failed

ProxyError: Conda cannot proceed due to an error in your proxy configuration.
Check for typos and other configuration errors in any '.netrc' file in your home directory,
any environment variables ending in '_PROXY', and any other system-wide proxy
configuration settings.
...
```
I have to use the proxy so that the remote server is connected to the Internet. I searched the internet there are some solutions that set the proxy in `.condarc` file. So I tried to set the location of the this file:
```bash
julia> Conda.conda_rc("/home/dongjx/.condarc")
ERROR: ArgumentError: Path to conda environment is not valid: /home/dongjx/.condarc
Stacktrace:
[1] prefix
@ ~/.julia/packages/Conda/kOnIE/src/Conda.jl:42 [inlined]
[2] conda_rc(env::String)
@ Conda ~/.julia/packages/Conda/kOnIE/src/Conda.jl:87
[3] top-level scope
@ REPL[6]:1
```
So how can I set proxy for `Conda.jl` to resume the installation?