axel， yum安装或者apt-get安装
但有时axel不行，需要上wget，但单线程的太慢，需要安装mwget。
apt-get -y install intltool
wget http://jaist.dl.sourceforge.net/project/kmphpfm/mwget/0.1/mwget_0.1.0.orig.tar.bz2
tar -xjvf mwget_0.1.0.orig.tar.bz2
cd mwget_0.1.0.orig
./configure
make
make install
mwget比wget速度，实测提升了至少4倍。因为缺省是4个线程，所以快了4倍。
选项是：
Options:
-b, --debug Show the debug message
-c, --count=num Set the retry count to [num], no limit when "0", the default is "99"
-d, --directory=dir Set the local direcotry to [dir], the default is "."
-f, --file=file Rename the file to [file]
-h, --help A brief summary of all the options
-i, --interval=num Set the ftp retry interval to [num] seconds, the default is "5"
-n, --number=num Use [num] connections instead of the default (4)
-r, --referer=URL Include `Referer: [URL]' header in HTTP request.
-t, --timeout=num Set the connection timeout to [num] seconds, the default is "30"
-v, --version Show the version of the mwget and exit
-x, --proxy=URL Set the proxy [URL]
写了个wget.sh，内容如下：
#!/bin/bash
if ! axel $*;then
mwget -n 8 $*
fi
用axel下载东西时，容易出现 Too many redirects. 的错误，这时候可以改用wget或者mwget。mwget没有下载完，退出，重新执行一次，就能断点续传了。