Can you help me to keep only these lines in which the preceding number appears only once? In the example above, I would keep the lines starting with 1,3 and 5.
That's seems contradictory. If you keep the lines starting with 1,3 and 5, then you keep the lines where the preceding number appears more than once.

Please explain better what you really want.

Je suis Charlie.

In reply to Re: Remove unique lines from file by Laurent_R
in thread Remove unique lines from file by Anonymous Monk

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