BATsh

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Changes  view on Meta::CPAN

    - eg/06_sh_comprehensive.batsh: I/O-redirection section simplified to a
      plain "while read" loop now that the loop terminates correctly.

    - Tests: t/9070-examples.t now executes each eg/*.batsh in a child
      process and guards against runaway output and "syntax error"
      breakage (E4). t/9060-readme.t verifies the README advertises every
      eg/ example by name (R5). README gains an EXAMPLES section.

    - SH background execution: an unquoted trailing "&" starts an external
      command asynchronously and returns immediately. On Win32 the job is
      spawned via system(1, ...) (P_NOWAIT, PID returned); on Unix it is
      started through /bin/sh without a Perl fork, capturing the job PID
      via the shell's $! into a sysopen O_CREAT|O_EXCL temp file (Pure
      Perl, 5.005_03). The new $! parameter expands to the most recent
      background PID (empty before any job); $? is 0 on a successful
      launch (the job's own exit status is not awaited). Built-ins,
      functions, assignments and control words ignore the trailing "&"
      and run in the foreground; "&&", ">&"/"2>&1", quoted and escaped
      "\&" are not treated as background. No job control; CMD-mode "&"
      remains a sequential separator (see BUGS AND LIMITATIONS).

lib/BATsh/SH.pm  view on Meta::CPAN

    # Shebang: treat as comment
    return 0 if $line =~ /\A#!/;

    # ----------------------------------------------------------------
    # Background execution: an unquoted trailing & (v1).
    # Detected here, BEFORE _split_sh_compound, so that the bare & is
    # never mistaken for && and so that an internal & (e.g. in 2>&1 or
    # >&2) is left untouched.  Only the single & at the very end of the
    # line is consumed.  Builtins / functions / control words / variable
    # assignments run in the FOREGROUND (the & is ignored); only external
    # commands are launched asynchronously.
    # ----------------------------------------------------------------
    my ($_is_bg, $_bg_line) = _split_trailing_bg($line);
    if ($_is_bg) {
        $line = $_bg_line;
        my $probe = $line;
        $probe =~ s/\A\s+//;
        my $w0 = '';
        ($w0) = ($probe =~ /\A(\S+)/);
        $w0 = '' unless defined $w0;
        if (_sh_word_is_foreground($w0)) {

lib/BATsh/SH.pm  view on Meta::CPAN

            close(_BG_TMP);
            push @_BG_TMPFILES, $path;
            return $path;
        }
        # EEXIST or transient error: retry with next sequence number
    }
    warn "sh: cannot create background pidfile in $dir: $!\n";
    return undef;
}

# _bg_launch: start $cmdline asynchronously.
#   Win32      : system(1, STRING) spawns via the command shell (P_NOWAIT)
#                and returns the PID directly.
#   Unix-like  : delegate to /bin/sh so the job is backgrounded without a
#                Perl fork; the shell's $! (the job PID) is written to a
#                temp file and read back into BATsh's own $!.
# On a successful launch $? (LAST_STATUS) is 0; the exit code of the
# background job itself is not awaited (sh semantics).
sub _bg_launch {
    my ($class, $cmdline) = @_;
    $cmdline = '' unless defined $cmdline;

lib/BATsh/SH.pm  view on Meta::CPAN

A here-document body line that looks like a BATsh subroutine marker
(a line of the form C<:LABEL> later followed by C<RET>/C<RETURN>) may be
consumed by subroutine extraction, which runs before mode dispatch.
Avoid such lines inside here-document bodies.

=back

=head2 Background Execution

An unquoted C<&> at the very end of an SH command line starts the command
asynchronously and returns control immediately, in the style of POSIX
shells:

  longjob &
  echo "next prompt"

Only the single C<&> at the end of the line is consumed.  An C<&> that is
part of C<&&>, of an fd-duplication such as C<2E<gt>&1> or C<1E<gt>&2>,
inside single or double quotes, or backslash-escaped (C<\&>) is B<not>
treated as a background operator and is left in place.