Question:

On a Linux system, Compilation terminated with this error:

 In file included from SWITCHER.c:21:
 includes.h:7: X11/Xos.h No such file or directory
 includes.h:9: X11/Xlib.h No such file or directory
 includes.h:10: X11/Xutil.h No such file or directory
 make[2]: *** [OBJ/SWITCHER.o] Error 1
 make[1]: *** [all] Error 2
 make: *** [do-install] Error 1
 
 There are no such filenames (Xos.h etc) anywhere on the system.
 What can I do?


Answer: 

At least in SuSe Linux distribution there is a package 
  "xdevel.rpm". 
It contains the files missing on your platform. I guess it is
existing in your Redhat distribution as well. Install this
package and proceed with compilation.