$ sudo pecl install redis Package "redis" does not have REST info xml available install failed
$ pecl search redis File http://pecl.php.net:80/rest/p/packages.xml not valid (redirected but no location)
If anyone else has a similar problem, it is solved now, it's the firewall. For any reason, I can download files from the browser, and I can install or update packages by APT, but firewall is blocking PEAR downloads. I have added PEAR URL's to secured sites and now it's working.
看到firewall is blocking PEAR downloads，就猜到估计是某墙的问题，打开VPN再试一下就OK了。