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How can I use GNU sort and uniq to have the most common occurrences on top instead of numerical or alphanumerical sorting? Example list.txt:

1
2
2
2
3
3

Since '2' occurs 3 times, should be on top, followed by '3' and '1' like this:

$ cat list.txt | "some sort/uniq magic combo"
2
3
1
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1 Answer 1

up vote 4 down vote accepted

Like this:

cat list.txt | sort | uniq -c | sort -rn

The -c includes the count of each unique line and then you sort by that.

If you want to remove the count after sorting, do so:

cat list.txt | sort | uniq -c | sort -rn | awk '{ print $2; }'
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I've been doing this for ages, and for moderate size tasks it works well. However every so often I find myself with gigabytes of log data to go through and doing a sort on that requires a lot of disk space that is for duplicate lines that you throw away in the next step. There are better algorithms, but I don't know good simple command line tools for solving this problem at a larger scale. –  mc0e Feb 18 at 15:48

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