下载 PECL 扩展库有几种方法，如：
jeremy dot crombez at gmail dot com (2012-03-19 17:17:31)
On Debian Squeeze, you can simply do :
aptitude install libssh2-php
mleer at clingendael dot nl (2009-09-18 04:11:26)
If you get "pear.php.net is using a unsupported protocal" [sic!] do:
cd /usr/local/lib/php
rm -r .channels
pear update-channels
cweiske at php dot net (2009-05-03 03:58:57)
When using "pecl install package", you might run into a memory limit problem. Solution is to use "pear install pecl/$extensionname" since it uses php.ini's memory limit.
See also:
- http://pear.php.net/bugs/bug.php?id=15107
- http://aspn.activestate.com/ASPN/Mail/Message/pear-dev/3168978