A few handy commands (tummy.com, ltd. Journal Entry)
tummy.com: we do linux

Friday November 19, 2004 at 13:52
Subject: A few handy commands
Keywords: Command Line, Tech
Posted by: Kevin Fenzi

Here's some handy commands I used today that perhaps not too many folks know about:

interdiff gives you a diff between two diff files. Great for checking if two patches are the same or what has changed between two versions of a patch. They have to be patches against the same file base, but still very handy.

openssl command line can be used to look at the information from a ssl cert .pem file, just do: 'openssl x509 -text -in /path/to/your/ssl/cert.pem' and it will dump out all kinds of information about the ssl cert.

mussh (which you can find at: http://sourceforge.net/projects/mussh/ ) allows you to run a command via ssh on a list of hosts. Handy for running things like 'yum check-update' or 'apt-get --dry-run upgrade'.
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Comment
Author: Sean Reifschneider
Subject: More on "openssl".

One of the things I use the "openssl" command for the most is testing services that have SSL enabled. You can use "openssl" from the command-line kind of like an SSL-enabled telnet:

openssl s_client -connect server.example.com:443

In the above example it opens a connection with "server.example.com" on it's SSL web port and then lets you talk to it. For example, you could then do "GET / HTTP/1.0", just as if you had done a "telnet server.example.com 80" to make a test connection to the non-SSL web server port.

Sean