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I am trying to search for consecutive, repeated instances of numbers in a file, with each number on a different line. It's easiest to show what I mean in an example.

For example, my input would be: 

16
16
8
8
16
16
4
8
8
8

And my output would be: 

16 2
8 2
16 2
4 1
8 3

This may appear to be a duplicate, but though I have found many solutions (like this one) for finding the repetitions of a single character, none of them are able to search for multiple repeated characters.

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  • Do you mean repeated characters (e.g. 111), repeated strings (e.g. 123123) or repeated lines? Will each line of your input only consist of a string of characters (including numbers) and no spaces? Do you just want repeated lines? Commented Jan 19, 2019 at 18:16
  • @terdon - it was a badly worded title - I meant to put repeated lines. My question sort of changed as I was writing the post. I'll edit the title. Commented Jan 19, 2019 at 18:25

1 Answer 1

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6

You can use uniq to do this, though the standard format of its output is slightly different.

$ < in uniq -c
      2 16
      2 8
      2 16
      1 4
      3 8

Assuming in is a file that contains the input, you'll get what you see above.

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  • which could be piped through awk '{print $2,$1}' for a quick'n'dirty way to get output in the order shown by the OP Commented Jan 19, 2019 at 18:25

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