wrap bash compound commands in bash -c before nohup

[meganrogge]

nohup can only exec external commands — it cannot run bash compound
statements (for, while, if, case, eval, export, etc.) or
shell builtins directly. Commands like:

nohup for i in $(seq 1 90); do echo $i; sleep 1; done &

fail silently because for is not an executable.

Adds _needsBashCWrapper() to detect compound constructs and builtins,
wrapping them as:

nohup bash -c 'for i in $(seq 1 90); do echo $i; sleep 1; done' &

Single quotes inside the command are escaped with the POSIX '\''
pattern.

Fixes eval regressions on terminal_long_running_prompt (confirmed
broken nohup rewrite) and improves reliability of all background
terminal commands involving shell syntax.

Only affects POSIX paths when chat.tools.terminal.detachBackgroundProcesses
is enabled (experimental, default off).

[Copilot]

Pull request overview

This PR improves the terminal background-detach command rewriter so that POSIX background commands using shell compound syntax or builtins (which nohup can’t exec directly) are wrapped in bash -c '...' before being passed to nohup, and adds coverage for these cases.

Changes:

• Add _needsBashCWrapper() detection for compound commands/builtins and wrap with bash -c '...' (including single-quote escaping).
• Adjust POSIX rewrite logic to run nohup against the wrapped command.
• Add a dedicated test suite covering compound constructs, builtins, grouping, and quote escaping.

Show a summary per file

File	Description
src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/commandLineRewriter/commandLineBackgroundDetachRewriter.ts	Adds detection + wrapping logic for compound commands/builtins before nohup.
src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/electron-browser/commandLineBackgroundDetachRewriter.test.ts	Adds tests verifying bash -c wrapping and correct escaping/behavior.

Copilot's findings

Comments suppressed due to low confidence (2)

src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/commandLineRewriter/commandLineBackgroundDetachRewriter.ts:90

• Comment says dot-source is detected by requiring “a space or end-of-string after the dot”, but the regex only matches ^\. (dot + space). Either update the comment, or adjust the regex to also match the . builtin with no arguments if that’s intended.

			// `. file` (dot-source builtin). Exclude `./script` (relative path) by requiring
			// a space or end-of-string after the dot.
			/^\. /.test(trimmed) ||
			// Compound groupings: subshell `( ... )` or brace group `{ ...; }`.

src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/commandLineRewriter/commandLineBackgroundDetachRewriter.ts:66

• endsWithBackgroundAmp is now tested against commandToWrap after wrapping. When the original command ends with a trailing & and _needsBashCWrapper is true, the & ends up inside the quoted bash -c '...&' string so the regex won’t match and an extra outer & gets appended (producing nohup bash -c '... &' &). Consider detecting/stripping a trailing background & from the original trimmed command before escaping/wrapping, and then only adding a single outer & to the final nohup invocation.

		let commandToWrap = trimmed;
		if (this._needsBashCWrapper(trimmed)) {
			// Escape single quotes for use inside a single-quoted bash -c '...' string.
			const escaped = trimmed.replace(/'/g, `'\\''`);
			commandToWrap = `bash -c '${escaped}'`;
		}

		// If the command already ends with a single trailing `&` (background operator,
		// as opposed to `&&` for command chaining), don't append another one.
		const endsWithBackgroundAmp = /(?:^|[^&])&$/.test(commandToWrap);
		const rewritten = endsWithBackgroundAmp
			? `nohup ${commandToWrap}`
			: `nohup ${commandToWrap} &`;

• Files reviewed: 2/2 changed files
• Comments generated: 1