1.42.5: no empty programs -- left behind, installed, or kept

Fixed

• A desktop of nought-byte programs. On an Alpine machine every program in /usr/local/bin was empty -- and so was every one in the source tree it was built from. A link had failed and left the empty file behind; make counted it as built and never tried again; make install put the lot in; and l2kdm --check on an empty file exits 0, so the installer walked past its own guard and enabled a logon screen that started and stopped in silence every two seconds. Every re-run of the installer after that changed nothing, because make had nothing to do.

  Three things now: .DELETE_ON_ERROR in the Makefile, so a recipe that fails takes its half-written target with it; the installer checks the shell, Explorer and the logon screen for emptiness after building and starts over from nothing if it finds any, which repairs a machine already in that state; and a program must have something in it to be installed at all.

If your machine is in that state, this is the whole cure -- or just run the one-liner again, which now does it for you:

cd /usr/local/src/Linux-explorer && make clean && make && make install

curl -fsSL https://jacktulli.github.io/w2k | sh