title: What libraries need to be linked for timer_create, timer_settime and other timer related functions
body: <p>Compiling a program on Linux that calls POSIX timer functions (eg: timer_create, timer_settime) returns errors such as:</p>
  
  <pre>
  In function `foo':
  timer.c:(.text+0xbb): undefined reference to `timer_create'
  timer.c:(.text+0x187): undefined reference to `timer_settime'
  collect2: ld returned 1 exit status
  </pre>
  
  <p>Which library do I need to link?</p>