The grep command is a command that most Linux users learn early on, and many times they learn to use it via pipes (stdin). Because of this some Linux users just assume that grep can only be used with stdin; it's ok, I was one of those too!
Before I continue with some grep tricks I want to clarify the basic grep usage.
Stop Doing This:
$ cat file.log | grep "something" something Do This More:...
In the world of Cloud Servers and Virtual Machines scripting and automation are top priority for any sysadmin. Recently while I was creating a script that logged into another server via SSH to run arbitrary commands, I ran into a brick wall.
$ ssh 192.168.0.169 The authenticity of host '192.168.0.169 (192.168.0.169)' can't be established. ECDSA key fingerprint is 74:39:3b:09:43:57:ea:fb:12:18:45:0e:c6:55:bf:58. Are you sure you want to continue connecting (yes/no)? To anyone who has used SSH long enough the above message should look familiar....