1、目标
conda会默认的安装perl和cpan，但是用conda安装的perl和cpan通常有问题，不能安装包
2、解决方法
不要用conda中的perl，修改.bash_profile文件，用系统默认的perl文件。
3、查看perl的安装环境
#(1) perl version
perl -v
This is perl 5, version 26, subversion 2 (v5.26.2) built for x86_64-linux-thread-multi
Copyright 1987-2018, Larry Wall
Perl may be copied only under the terms of either the Artistic License or the GNU General Public License, which may be found in the Perl 5 source kit.
Complete documentation for Perl, including FAQ lists, should be found on this system using "man perl" or "perldoc perl". If you have access to the Internet, point your browser at http://www.perl.org/, the Perl Home Page.
#(2) perl environment
perl -V
Summary of my perl5 (revision 5 version 26 subversion 2) configuration:
Platform:
osname=linux
osvers=4.15.0-1098-azure
archname=x86_64-linux-thread-multi
.......
#(3) gcc version
perl -V:cc
cc='~/anaconda3/bin/..//bin/x86_64-conda-linux-gnu-gcc';
#（4）install perl package using default cpan
/usr/bin/cpan XML::DOM
