The idea came from watching Jiayi Weng’s invitation talk — a candid walkthrough of his journey through open-source projects (Tianshou), research infrastructure, and post-training at OpenAI. It reminded me that writing things down, even informally, is a worthwhile habit.

Since we don’t have sudo access, we need to install npm via conda in a dedicated environment. Also, we need to set up global access to the npm binaries to avoid conda env PATH conflicts.

Install npm via conda

conda create -n basic_tools python=3.11
conda activate basic_tools
conda install npm

Set up global access

Create a dedicated tool directory and symlink only the needed binaries, avoiding conda env PATH conflicts:

mkdir -p ~/toolsmiao

# symlink node and npm
ln -s $(conda env list | grep basic_tools | awk '{print $NF}')/bin/node ~/toolsmiao/node
ln -s $(conda env list | grep basic_tools | awk '{print $NF}')/bin/npm ~/toolsmiao/npm

Add to your shell config (~/.bashrc):

export PATH=$HOME/toolsmiao:$HOME/toolsmiao/bin:$PATH

Install Claude Code and Codex

# set global install prefix to ~/toolsmiao
npm config set prefix ~/toolsmiao

npm install -g @anthropic-ai/claude-code
npm install -g @openai/codex

This way claude and codex binaries land directly in ~/toolsmiao/bin/ — no conda activation needed after the initial setup.

Prerequisites

1. Add RemoteForward to Your SSH Config

Open ~/.ssh/config on your local machine.

Add RemoteForward 7890 127.0.0.1:7890 to every Host block you connect to:

Host chpc-login
    HostName chpc-login.itsc.cuhk.edu.hk
    User YOUR_COMPUTING_ID
    IdentityFile ~/.ssh/id_ed25519
    IdentitiesOnly yes
    ControlMaster auto
    ControlPersist 10m
    RemoteForward 7890 127.0.0.1:7890   # ← add this line

Host chpc-gpu0?? chpc-gpu0??.rc.cuhk.edu.hk
    HostName %h.rc.cuhk.edu.hk
    User YOUR_COMPUTING_ID
    IdentityFile ~/.ssh/id_ed25519
    IdentitiesOnly yes
    ProxyJump chpc-login
    RemoteForward 7890 127.0.0.1:7890   # ← add this line

Host chpc-cn??? chpc-cn???.rc.cuhk.edu.hk
    HostName %h.rc.cuhk.edu.hk
    User YOUR_COMPUTING_ID
    IdentityFile ~/.ssh/id_ed25519
    IdentitiesOnly yes
    ProxyJump chpc-login
    RemoteForward 7890 127.0.0.1:7890   # ← add this line

Note: 7890 must match your local proxy’s mixed port. In Clash, check Settings → Mixed Port.

RemoteForward makes port 7890 on the remote machine forward traffic back to 127.0.0.1:7890 on your laptop. Combined with ProxyJump, the forward propagates through the jump chain, so compute nodes get the proxy too.

2. Export Proxy Variables on the Remote Server

For bash or zsh, append to ~/.bashrc / ~/.zshrc:

export HTTP_PROXY="http://127.0.0.1:7890"
export HTTPS_PROXY="http://127.0.0.1:7890"
export ALL_PROXY="socks5://127.0.0.1:7890"

Reload the config (source ~/.bashrc, etc.) or open a fresh terminal.

3. Verify

Reconnect to the server via VS Code Remote SSH, then run:

curl -x http://127.0.0.1:7890 https://api.anthropic.com
# or, for Codex:
curl -x http://127.0.0.1:7890 https://api.openai.com

Any response — even an HTTP error body — means the tunnel is alive. Claude Code and Codex can now reach the internet.

Alternative: Codex-Specific .env (If Shell Variables Fail)

If Codex still can’t reach the API after setting shell variables (e.g. when launched from an IDE plugin or non-interactive context), create ~/.codex/.env:

tee ~/.codex/.env <<'EOF'
http_proxy="http://127.0.0.1:7890"
https_proxy="http://127.0.0.1:7890"
all_proxy="socks5://127.0.0.1:7890"
EOF
chmod 600 ~/.codex/.env

This file is loaded automatically when Codex starts — independent of your shell environment.

Format rules:

• One variable per line, values in double quotes
• Do not use export
• Do not omit the quotes

This approach is process-level rather than session-level, so it won’t pollute other tools (curl, apt, etc.) in the same shell.

FAQ

Easily save tmux scrollback to a file so you can review logs or share them with AI for debugging.

The Problem

When running programs inside tmux, viewing and copying output is cumbersome — you have to enter scroll mode, navigate manually, and copy-paste is unreliable for large outputs.

Solution: Capture Pane to File

In your tmux session, press Ctrl+B then : to open the command prompt, and run:

capture-pane -S -2000 ; save-buffer log.txt

Adjust -2000 to capture more or fewer lines (e.g. -S -5000 for 5000 lines, or -S - for the entire scrollback history).

Use Case

This is particularly useful when you need to debug errors but aren’t sure how to fix them — save the output to a file, then feed it to an AI tool for analysis:

# Inside tmux: Ctrl+B : capture-pane -S -2000 ; save-buffer log.txt

# Then ask Claude Code to help debug
claude "check log.txt and help me fix the errors"