我试图使用wget通过远程服务器（ssh）从github检索一些文件，这是我得到的：
$ wget https://raw.githubusercontent.com/aseemk/seadragon-ajax/master/seadragon-min.js
--2014-11-26 09:30:14-- https://raw.githubusercontent.com/aseemk/seadragon-ajax/master/seadragon-min.js
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 185.31.19.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|185.31.19.133|:443... connected.
ERROR: The certificate of `raw.githubusercontent.com' is not trusted.
ERROR: The certificate of `raw.githubusercontent.com' hasn't got a known issuer.
同样适用于卷曲：
$ curl -o bla https://raw.githubusercontent.com/aseemk/seadragon-ajax/master/seadragon-min.js
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (60) SSL certificate problem: unable to get local issuer certificate
More details here: http://curl.haxx.se/docs/sslcerts.html
curl performs SSL certificate verification by default, using a "bundle"
of Certificate Authority (CA) public keys (CA certs). If the default
bundle file isn't adequate, you can specify an alternate file
using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
the bundle, the certificate verification probably failed due to a
problem with the certificate (it might be expired, or the name might
not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
the -k (or --insecure) option.
使用wget选项：--no-check-certificate似乎是一个黑客，我可以缺少什么？
解决方案很简单，从我的debian系统中简单安装：
$ sudo apt-get install ca-certificates
我在raspbian上遇到了这个问题，修复了它：
sudo apt-get install ssl-cert