Linux / UNIX File Formats

I‘ve followed your guide and installed denyhosts to protect on my RedHat 5.3 OpenSSH based server. However, I’ve been accidentally blocked out from my home ADSL IP address. I tried removing my blocked IP from /etc/hosts.deny, but it did blocked it again quickly. It appears that DenyHosts keeps track of the attempts somewhere on disk or memory. How do I remove my own home IP address from DenyHosts?
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Q. I’m new to GNU/Linux world and a single query (apt-cache search office or yum search ‘office’) shows so many application for a single task such as network monitoring or office applications. The number of apps choices just confusing. How do you select application from so many choices?
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I am a new Unix system user with a bash as a default shell. I can append text to a file using >> operator but how do I prepend a text to a file? I want the opposite operation of >>. How can I prepend some data to a text file? How do we add text to the beginning of a file in Bash under Linux?
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