PiDP-8/I Software

	  done \
	)
	@sed -e 's#^build =.*#build = "@ABSPREFIX@"#' \
	     -e 's#^media =.*#media = os.path.join (build, "share/media/")#' \
	     -e 's#^os8mo =.*#os8mo = os8mi#' \
		 < $(PIDP8I_DIRS) > @prefix@/$(PIDP8I_DIRS)
	@chgrp @INSTGRP@ @prefix@/$(PIDP8I_DIRS)

	@# We need a directory for PIDs and such in some cases
	@@INSTALL@ -d -m 755 @prefix@/run

instdirs:
	@echo "Creating installation directory tree..."
	@for d in $(INSTDIRS) ; do @INSTALL@ -m 755 -o @INSTUSR@ -g @INSTGRP@ -d @prefix@/$$d ; done

mediainstall: instdirs
	@echo "[Re]installing OS and program media..."

The `SCREEN_MANAGER` setting is for use by those that need something
other than GNU `screen`. There are several alternatives:

*   **screen**: The default, per above.

*   [**tmux**][tmux]: A popular alternative to `screen`, especially on
    BSD platforms.

*   [**`dtach`**][dtach]: A minimalist alternative to `screen` which
    provides only its terminal attach/detach features.

    In addition to the virtues called out on the program’s home page,
    use of this option has a side benefit for some PiDP-8/I users:
    `screen` and `tmux` assume an [ANSI X3.64 terminal][ansit] (e.g. DEC
    VT102 or xterm), because they interpret escape codes to provide
    features such as their scrollback buffer. It is uncommon to find
    PDP-8 software that uses ANSI terminal escape codes since almost all
    PDP-8 computers sold predate that standard. Most PDP-8 software
    assumes a dumb teletypewriter, and of the software that does make
    use of a smart terminal, there’s a good chance it wants something
    else, such as a [Tek 4010][t4010] series terminal. These ANSI screen
    managers can therefore get in the way and mess things up.

    `dtach` doesn’t interfere with terminal escape code handling; thus
    this option.

    Unlike `screen` and `tmux`, there is no command layer enetered
    via an "attention" keystroke in `dtach`. The only key that `dtach`
    scans for from the terminal is the detach keystroke, which we leave
    at its default, <kbd>Ctrl-\\<kbd>.

*   **none**: This mode is for interactive use, allowing you to
    run the installed simulator with the installed media without any
    screen manager at all.

    In this mode, the `pidp8i` and `pidp8i start` commands do the
    same thing: run the simulator directly attached to your current

Raspbian, this is done by:

    $ sudo apt install tmux

Switching between configured screen managers must be done while the
simulator is stopped.

[ansit]: https://en.wikipedia.org/wiki/ANSI_escape_code
[dtach]: https://github.com/crigler/dtach
[gscr]:  https://www.gnu.org/software/screen/
[scons]: /wiki?name=Serial+or+Telnet+PDP-8+Console
[t4010]: https://en.wikipedia.org/wiki/Tektronix_4010
[tmux]:  https://tmux.github.io/


## <a id="os8di"></a>The OS/8 RK05 Disk Image

For the first several years of the PiDP-8/I project, the OS/8 RK05 disk
image included with the PiDP-8/I software (called `os8.rk05`) was based

bootdir="@BOOTDIR@"
prefix="@ABSPREFIX@"
sim="$prefix/bin/pidp8i-sim"
scanswitch="$prefix/libexec/scanswitch"
systemctl=$(uname -r | grep -qw Microsoft && echo /bin/nothing || echo /bin/systemctl)
ggrep=$(which ggrep grep 2> /dev/null | head -1)
dtsock=$prefix/run/pidp8i-dtach.sock

if [ -e "$prefix/etc/pidp8i.rc" ]
then
    . "$prefix/etc/pidp8i.rc"
fi
[ -n "$SCREEN_MANAGER" ] || SCREEN_MANAGER=screen
if [ ! -t 1 ] && [ "$SCREEN_MANAGER" = "none" ]
then
    echo "The 'none' screen manager mode is meant for interactive use only!"
    exit 1
fi

is_running() {
    if [ "$SCREEN_MANAGER" = "none" ]
    then
        return 1
    elif [ "$SCREEN_MANAGER" = "tmux" ]
    then
        tmux has-session -t pidp8i 2>/dev/null
    elif [ "$SCREEN_MANAGER" = "dtach" ]
    then
        test -e $dtsock
    else
        procs=`screen -list pidp8i | $ggrep -Pc '\d\.pidp8i'`
        test -n "$procs" && test $procs -gt 0 && return 0 || return 1
    fi
}

sim_child_pid() {
    if [ "$SCREEN_MANAGER" = "none" ]
    then
        echo ""
    elif [ "$SCREEN_MANAGER" = "tmux" ]
    then
        tmux list-sessions -F '#{session_name} #{pid}' | awk '/^pidp8i / {print $2}'
    elif [ "$SCREEN_MANAGER" = "dtach" ]
    then
        test -e $dtsock && fuser -f $dtsock | cut -f2 -d' '
    else
        screen -ls pidp8i | grep -Eo '[[:digit:]]+\.pidp8i' | grep -Eo '^[[:digit:]]+'
    fi
}

# Were we given a command line argument?
if [ -z "$1" ]
then
    # No, so try to run or attach to the running simulator
    if [ "$SCREEN_MANAGER" = "none" ]
    then
        exec $0 start
    elif is_running
    then
        echo Joining simulator session already in progress...
        if [ "$SCREEN_MANAGER" = "tmux" ]
        then
            exec tmux attach-session -d -t pidp8i
        elif [ "$SCREEN_MANAGER" = "dtach" ]
        then
            exec dtach -a $dtsock
        else
            exec screen -r -S pidp8i
        fi
    else
        cat <<ERROR
Either the simulator isn't running, or it isn't running under a ${SCREEN_MANAGER}
session owned by @INSTUSR@.  Did you start the simulator via systemd?

    # Start the simulator
    if [ "$SCREEN_MANAGER" = "none" ]
    then
        exec "$sim" "$bscript"
    elif [ "$SCREEN_MANAGER" = "tmux" ]
    then
        tmux new-session -s pidp8i -d "$sim" "$bscript"
    elif [ "$SCREEN_MANAGER" = "dtach" ]
    then
        dtach -n $dtsock -z "$sim" "$bscript"
    else
        screen -dm -S pidp8i "$sim" "$bscript"
    fi

    # Tell systemd where to find the backgrounded simulator so it can
    # stop it via systemctl.  Skipped on non-systemd systems and where
    # SCREEN_MANAGER=none.

# PiDP-8/I runtime configuration file.  See it README.md file or
# https://tangentsoft.com/pidp8i/doc/trunk/README.md#runtime

# Alternatives: dtach, none, tmux
SCREEN_MANAGER=screen