Days between 2 unix epoch

#!/bin/bash
# Calculate "days diff" (unix epoch)
function daysdiff {
    begin=${1:-0}
    end=${2:-0}
    let Sec=$end-$begin

    if ((Sec < 0)); then
      echo $((Sec/-86400))
    else
      echo $((Sec/86400));
    fi
    return 0
}

Working with date in shell

If you don't know what time is the unix time 1245257034

<br /><br />$ date -d @1245257034<br />Wed Jun 17 12:43:54 EDT 2009<br /><br />

Or in UTC

$ date -d @1245257034 -u
Wed Jun 17 16:43:54 UTC 2009

To know what is the current unix time in your machine

$ date +%s
1245257175