```
$ echo $PATH
/sbin:/usr/bin:/usr/sbin:/usr/sfw/bin:/usr/sfw/sbin:/opt/csw/bin:/opt/csw/sbin:/usr/openwin/bin:/usr/ccs/bin:/usr/local/bin:/opt/onbld/bin:/opt/onbld/bin/i386:/opt/solstudio12.2/bin
$ which ctags
/usr/bin/ctags
$ which exctags
/usr/bin/exctags
$ ctags --version
-v: No such file or directory
-e: No such file or directory
-r: No such file or directory
-s: No such file or directory
-i: No such file or directory
-o: No such file or directory
-n: No such file or directory
$ exctags --version
Exuberant Ctags 5.8, Copyright (C) 1996-2009 Darren Hiebert
  Compiled: Feb  9 2010, 12:38:07
  Addresses: <dhiebert@users.sourceforge.net>, http://ctags.sourceforge.net
  Optional compiled features: +wildcards, +regex
$ ./OpenGrok index
Loading the default instance configuration ...
```