keywords: whereis , path , 路径， linux, 终端， terminal
例子：
gangcai@gangcai-laptop:/usr/bin$ whereis R
R: /usr/bin/R /etc/R /usr/lib/R /usr/local/lib/R /usr/share/R /usr/share/man/man1/R.1.gz
gangcai@gangcai-laptop:/usr/bin$ whereis perl
perl: /usr/bin/perl /etc/perl /usr/lib/perl /usr/share/perl /opt/ActivePerl-5.8/bin/perl /usr/share/man/man1/perl.1.gz
