How to Find the Time Between two Unix Time Stamps

This article explains how to find the time interval between two Unix time stamps. The default time format in Unix is like this: “Sun 9 Aug 12:50:08 BST 2020”. It appears in many places on the system and is the default produced by the “date” command.

For example, it might appear in application log files, like this::

Start time: Sun 9 Aug 10:05:00 BST 2020
End Time:   Sun 9 Aug 12:51:12 BST 2020

This article explains how to subtract one time from the other in Bash, and obtain the intervening time in seconds.

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Sorting with "-k" on Unix and Linux

The “sort” command on Solaris has a “-k” switch for sorting by a particular field. For example, “sort -k 2” will sort by the second field on each line of input. Parts of fields can be further specified with “-k n.m“, says the man page.

For example, “sort -k 2.3” should sort by the second field, starting with the third character in that field. But the man page isn’t the clearest, and getting the “-k x.y” notation to work is tricky. Tricky until you realize it never works you also supply the “-b” argument. Same on Linux. Continue reading