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How do I verify and diagnosis SSL certification installation from a Linux / UNIX shell prompt? How do I validate SSL Certificate installation and save hours of troubleshooting headaches without using a browser? How do I confirm I've the correct and working SSL certificates?

OpenSSL comes with a generic SSL/TLS client which can establish a transparent connection to a remote server speaking SSL/TLS. It’s intended for testing purposes only and provides only rudimentary interface functionality but internally uses mostly all functionality of the OpenSSL ssl library. For testing purpose I will use mail.nixcraft.net:443 SSL certificate which is issued by Go Daddy.

在linux的文字窗口中，使用telnet，有时会发现输入的中文会变成乱码，
此时加入参数 -8 就可以解决，例如：

telnet -8 bbs.xxx.xxx
也可以设 ~/.telnetrc 来解决，把底下设定加入 ~/.telnetrc 就可以了，
下次telnet就不用再加参数 -8

DEFAULT set binary

How to build jpegsrc.v6b on 64-bit Linux machines
jpegsrc is no longer maintained and has not been updated since the Clinton administration. This is odd considering how critical this library is to so many applications.

If you are trying to build on a 64-bit Linux machine you will probably get this error during the ./configure step:

checking host system type... Invalid configuration `x86_64-unknown-linux-gnu': machine `x86_64-unknown' not recognized

制作简单的安装包的时候可以简单的用cat命令连接两个文件，
然后头部是脚本文件，执行的时候把下面的文件分解出来就行了。
一般这个后部分的文件是个压缩包，那样，就能够打包很多文件了，在脚本中解压出来即可。
这就是Linux那些bin啊run啊等安装脚本的简单制作了。

症状：

当NFS SERVER服务停止或者是NFS SERVER宕机，NFS Client 中一些涉及到挂载目录的命令可能会被挂起，如df、ls等。

解决办法：

可以使用mount -l列出挂载的目录，卸载掉已经停止NFS服务的目录

[root@test01 ~]# mount -l
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/sda1 on /boot type ext3 (rw) [/boot]
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
192.168.146.250:/home/share on /mnt type nfs (rw,addr=192.168.146.250)

[root@test01 ~]# umount -l /mnt/ #卸载
[root@test01 ~]# mount -l      
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/sda1 on /boot type ext3 (rw) [/boot]
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

解决Centos5上升级Python后yum不能用的问题

There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
 
 No module named yum
 
Please install a packagewhich provides this module, or
verify that the module is installed correctly.
 
It's possible that the above module doesn't match the
current version of Python, which is:
2.6.5 (r265:79063, Jul  22010, 16:30:56)[GCC 4.1.2 20080704(Red Hat 4.1.2-46)]If you cannot solve this problem yourself, please go to
the yum faq at:
 http://wiki.linux.duke.edu/YumFaq

htop - an interactive process viewer for Linux

This is htop, an interactive process viewer for Linux. It is a text-mode application (for console or X terminals) and requires ncurses. Tested with Linux 2.4 and 2.6.

官方网站：http://htop.sourceforge.net/
　　可以进行水平或竖直滚动 （总算可以看到所有进程和全部命令行了）
　　可以跟踪进程 （通过集成strace实现）
　　主页面上显示常用功能项，很方便。top里可以要'h'一下。
　　支持进程树状显示
　　可以按名称查找进程
　　支持鼠标
　　htop很不错，但还可以做得更好，下面是我想要的功能：
　　显示进程打开的文件
　　显示进程内存映射情况
　　更完整的man手册（比如设置更新周期的命令行选项'-d'就没有在手册中说明）
　　P.S. strace是个宝贝。单独做一个strace前端本身就是个不错的项目，支持对strace结果的分类，查询等功能。