Executable scripts with #!$^X are interpreted as shell scripts

[fglock]

Summary

PerlOnJava cannot execute generated executable Perl scripts whose shebang points to $^X. The host falls back to interpreting the script as a shell script, producing use: command not found and shell syntax errors.

Reproduction

Distribution: CLI::Cmdline 1.30

The upstream t/05-integration.t test writes an executable script.pl with:

print $fh "#!$^X\n";

It then executes the script directly. Under system Perl, all 275 tests pass. Under PerlOnJava, the five parser test files pass, but t/05-integration.t fails 22 of 25 assertions on both backends:

./script.pl: line 2: use: command not found
./script.pl: line 3: use: command not found
./script.pl: line 4: syntax error near unexpected token `('

The resulting exit status is 2 instead of the expected Perl-script results.

The issue reproduces with both the JVM backend and the interpreter backend. The failure is in executable-script/process-launch handling; CLI::Cmdline option parsing itself passes.

CPAN evidence

• CPAN random tester run: 20260907-214651-8410
• Target: CLI::Cmdline
• Upstream result under system Perl: 275/275 tests passed
• PerlOnJava result: 253/275 passed; 22 failures, all in t/05-integration.t

Expected behavior

An executable script with a PerlOnJava $^X shebang should be launched by PerlOnJava and execute as Perl, matching system Perl behavior.