How to group from file by some condition or get count of unique data
For example you have file which contains log of some events. Input data: Dec 9 00:33:42 some log Dec 9 00:56:49 some log Dec 9 01:13:12 some log Dec 9 01:22:02 some log Dec 9 01:35:52 some log Dec 9 03:15:52 some log Dec 9 12:17:52 some log And you want group this file by hours. The code below will help group and display data: grep -oP "Dec\s+9\s(\d{2})" | sort | uniq -c Output data: 2 Dec 9 00 3 Dec 9 01 1 Dec 9 03 1 Dec 9 12 First column - it's count of unique lines with the date. Flag -o is required to output only the requested substring (Dec\s+9\s(\d{2})) Flag -P is required for enable perl-style regexes Command sort sorts the data. And uniq -c find count of unique lines. Thank you for reading. Best regards, Ildar.