title: /bin/sh: VARIABLE: command not found
body: <p>I have the following target, in my Makefile:</p>
  
  <pre><code>~/.zshrc: zsh/*
      DESTDIR ?= $(shell echo '~/.') 
      SUDO ?= $(shell echo '') 
      sed -e "s_DESTDIR_$(DESTDIR)_" \
          -e "s_SUDO_$(SUDO)_" \
          -e "s_LIBDIR_$(LIBDIR)_" \
          -e '/^#/ d' $+ &gt; $@
  </code></pre>
  
  <p>But whenever I run <code>make ~.zshrc</code> I get the following error:</p>
  
  <pre><code>DESTDIR ?= ~/. 
  /bin/sh: DESTDIR: command not found
  make: *** [/Users/henrikgiesel/.zshrc] Error 127
  </code></pre>
  
  <p>I have no clue what causes this. Do I have to escape something? I have <code>PWD ?= $(shell pwd)</code> at another point in the file and it works just fine.</p>