You have a a column of numbers that you have produced in some manner such as :-
$ awk '/clean message/ {print $(NF-1)}' mail.info.log
...
100935
12197
3606
84653
4498
99110
4762
3001
10889
12611
12249
12245
136599
49097
6668
And you want a quick and dirty way of finding the largest number. Well there is a way but it is perhaps the least efficient way to do it, and that is to sort the numbers into numerical order and use “head” to display the first one :-
$ awk '/clean message/ {print $(NF-1)}' mail.info.log | sort -rn | head -1
5476168
But frankly there must be a better method. And yes there is if you happen to be using zsh (or possibly others, but this has been tested with zsh). Simply iterate over the values assigning the current value to the “max” variable if the current variable is larger :-
$ max=0; for x in $(awk '/clean message/ {print $(NF-1)}' mail.info.log); [[ $x -gt $max ]] && max=$x; echo $max
5476168
You may be wondering why I don’t simply use the ability of awk to perform calculations. Well that is certainly possible, but I may not always be using awk to produce the numbers in the first place, and this is supposed to be a generic recipe.