title: What's the script language inside kernel Makefile?
body: <pre><code>55 ifeq ("$(origin C)", "command line")
  56   KBUILD_CHECKSRC = $(C)
  57 endif
  58 ifndef KBUILD_CHECKSRC
  59   KBUILD_CHECKSRC = 0
  60 endif
  </code></pre>
  
  <p>In normal bash,there's no keywords like <code>ifndef</code>...</p>