Question: how to save url history in firefox withou being erased.? frequently I find that the url history suddenly vanishes.

Answer: If the history is disappearing, check to see how long you have set Firefox to remember the URLs under Tools > Options > Privacy tab. If Firefox crashes, the files that hold the history and other settings may be damaged. To save the history file, you will need to find where your profile is saved and copy history.dat from it.
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