Function rearrangePipeCommand

src/utils/bash/bashPipeCommand.ts:14–100

(command: string)

 * causing the stdin redirect to apply to eval itself rather than the first command.
 */
export function rearrangePipeCommand(command: string): string {
  // Skip if command has backticks - shell-quote doesn't handle them well
  if (command.includes('`')) {
    return quoteWithEvalStdinRedirect(command)
  }

  // Skip if command has command substitution - shell-quote parses $() incorrectly,
  // treating ( and ) as separate operators instead of recognizing command substitution
  if (command.includes('$(')) {
    return quoteWithEvalStdinRedirect(command)
  }

  // Skip if command references shell variables ($VAR, ${VAR}). shell-quote's parse()
  // expands these to empty string when no env is passed, silently dropping the
  // reference. Even if we preserved the token via an env function, quote() would
  // then escape the $ during rebuild, preventing runtime expansion. See #9732.
  if (/\$[A-Za-z_{]/.test(command)) {
    return quoteWithEvalStdinRedirect(command)
  }

  // Skip if command contains bash control structures (for/while/until/if/case/select)
  // shell-quote cannot parse these correctly and will incorrectly find pipes inside
  // the control structure body, breaking the command when rearranged
  if (containsControlStructure(command)) {
    return quoteWithEvalStdinRedirect(command)
  }

  // Join continuation lines before parsing: shell-quote doesn't handle \<newline>
  // and produces empty string tokens for each occurrence, causing spurious empty
  // arguments in the reconstructed command
  const joined = joinContinuationLines(command)

  // shell-quote treats bare newlines as whitespace, not command separators.
  // Parsing+rebuilding 'cmd1 | head\ncmd2 | grep' yields 'cmd1 | head cmd2 | grep',
  // silently merging pipelines. Line-continuation (\<newline>) is already stripped
  // above; any remaining newline is a real separator. Bail to the eval fallback,
  // which preserves the newline inside a single-quoted arg. See #32515.
  if (joined.includes('\n')) {
    return quoteWithEvalStdinRedirect(command)
  }

  // SECURITY: shell-quote treats \' inside single quotes as an escape, but
  // bash treats it as literal \ followed by a closing quote. The pattern
  // '\' <payload> '\' makes shell-quote merge <payload> into the quoted
  // string, hiding operators like ; from the token stream. Rebuilding from
  // that merged token can expose the operators when bash re-parses.
  if (hasShellQuoteSingleQuoteBug(joined)) {
    return quoteWithEvalStdinRedirect(command)
  }

  const parseResult = tryParseShellCommand(joined)

  // If parsing fails (malformed syntax), fall back to quoting the whole command
  if (!parseResult.success) {
    return quoteWithEvalStdinRedirect(command)
  }

  const parsed = parseResult.tokens