A Data URL Can Carry a Small PAC Policy at Chrome Startup

Chromium’s PAC loader accepts data URLs containing script bytes. For a small UTF-8 PAC file, a Bash launch using GNU base64 can prepare the argument locally:

pac64=$(base64 -w0 "$HOME/.config/proxy.pac")
google-chrome --proxy-pac-url="data:application/x-ns-proxy-autoconfig;charset=utf-8;base64,$pac64"

Use the installed browser’s executable name. GNU base64’s -w0 removes output wrapping; other base64 implementations can use different options. The charset declaration tells the PAC loader how to interpret the decoded bytes.

This embeds a snapshot of the file in a launch argument. Changing the file afterward does not update that running browser’s policy. Regenerate the argument for the next intended launch.

Launch into the intended fresh browser process. Handing a URL to an existing instance does not establish that it adopted new startup flags.

Keep this approach for policies that fit comfortably within command-line limits. A maintained HTTP or HTTPS PAC location is another delivery model, with its own retrieval path. No disabled Network Service flag is required for the data-URL mechanism.