which whereis locate
[root@localhost ~]# which ipppd
/sbin/ipppd
[root@localhost ~]# whereis ipppd
ipppd: /sbin/ipppd /usr/sbin/ipppd /usr/share/man/man8/ipppd.8.gz
[root@localhost ~]# locate signal.h
/usr/src/kernels/2.6.9-78.EL-i686/include/linux/signal.h
/usr/src/kernels/2.6.9-78.EL-i686/include/asm-i386/signal.h
/usr/src/kernels/2.6.9-78.EL-smp-i686/include/linux/signal.h
/usr/src/kernels/2.6.9-78.EL-smp-i686/include/asm-i386/signal.h
/usr/src/kernels/2.6.9-78.EL-hugemem-i686/include/linux/signal.h
/usr/src/kernels/2.6.9-78.EL-hugemem-i686/include/asm-i386/signal.h
/usr/share/doc/SDL-devel-1.2.7/html/sdlcondsignal.html
/usr/share/man/man0p/signal.h.0p.gz
/usr/include/valgrind/pub_tool_libcsignal.h
/usr/include/asm/signal.h
/usr/include/sys/signal.h
/usr/include/linux/signal.h
/usr/include/glib-2.0/gobject/gsignal.h
/usr/include/boost/signal.hpp
/usr/include/signal.h
