Using awk to work on data files

In order to average numbers in a file we can use awk as so:

$ cat meyer-heavy.txt | awk '{ sum+=$1;count++ } END {print sum/count}'

To find the largest value:

$ cat meyer-heavy.txt | awk 'BEGIN{max=-9999} $1 > max {print $1; max=$1}' 

Improved version (only prints largest value, not intermediate ones): 

$ cat meyer-heavy.txt | awk 'BEGIN{max=-9999} $1 > max {max=$1} END{print max}'

To find the smallest value:

$ cat meyer-heavy.txt | awk 'BEGIN{min=9999} $1 < min { print $1; min=$1 }' 

Fixed version (doesn't assign blank lines as min value): 

$ cat meyer-heavy.txt | awk 'BEGIN{min=9999} /\-[0-9]+/&&$1 < min { min=$1 } END{print min}'

Where $1 is for column 1, use $2 for column 2 etc...

Parsing columns in BASH

I sometimes need "cut" functionality that works for fields with more than a single space. For instance, I sadly have a script just to kill nepomukindexer because it constantly goes berzerk and uses all my 8gb of ram. 

So I need to parse the process IDs of all the processes that contain the word nepomukindexer (there are hundreds at times).

First try

I figured cut would do the trick.

ps -ef | grep nepomukindexer | cut -d " " -f 5 

This only works if there are exactly 4 spaces between the two fields, and that isn't always the case.

Second try

I still don't understand why sed doesn't seem to work with the "+" regular expression symbol the way I expect. The following seems like it should replace all instances of one or more spaces with a single space, but it does nothing.

ps -ef | grep nepomukindexer | sed 's/ +/ /g'

Edit: I just found a workaround for this. I changed this to

ps -ef | grep nepomukindexer | sed 's/  */ /g'
                                      ^^ two spaces

and it worked, the only difference being the matching part which says match a single space followed by 0 or more additional spaces, and replace the whole mess with a single space.

Third try

The solution I found is to use awk.

ps -ef | grep nepomuk | awk -F" " '{print $2}'

Using this command, I pipe the results through kill and all is well.