Help with awk

[dresden0526]

So the goal of this script is to figure out when a script has started or ended by comparing two intermediate files

The first scan of the ps will always be marked with as started so I used the following code to accomplish that:

echo "DATE: $CURRENT" > spy.txt
ps axo user,pid,comm >> spy.txt
echo " " 

echo " " > current.txt

for array in ${array[at symbol]} #still cannot print at symbols in posts
do
    grep "$array" spy.txt >> current.txt
done

head -1 spy.txt >> out.txt
for array in ${array[at symbol]} 
do
    grep "$array" current.txt | sed "s/^/Started:/">> out.txt
done

The next part is tricky I need to compare the two scans and if it started then it prints out : Started: user pid command

If it ended it should print out : Ended: user pid command

If it did nothing then all it should do is print the date of the scan and a blank line:
Date

I thought I could use the following code to show the differences :

awk 'NR==FNR{a[$1]++;next;}!($0 in a)' last.txt current.txt|sed "s/^/Ended:/" >> out.txt
	 	
awk 'NR==FNR{a[$1]++;next;}!($0 in a)' current.txt last.txt|sed "s/^/started:/" >> out.txt

But all that does is print that it both started or ended

Is there a better way to do this?

Is there some loop or if logic I could use to implement this section?

[atreyu]

Hi,

Quite apart from your awk question, what exactly are you trying to accomplish? All your output redirections make me queasy.

Also, unless you are not showing some of your code, that @array is not defined yet, so neither of those loops would run anyway (as shown).

[dresden0526]

Well the code is quite unsettling as I am quite a novice, but the goal is to run the ps command and search the scans for comnmand line strings. Then each time the loop runs the last scan and the first scan are compared and the results are output in a file. The output has to be formatted in a way that if there is a difference between the scans the output has to say

started user, pid, comm
ended user, pid, comm

And if there is no difference the output is just the date of the scan

I can include my entire code, but it is not pretty and will probably make you more queasy

#!/bin/bash
trap "rm psmonitor.txt; echo Interupt encountered, exiting;  exit 1" SIGHUP SIGINT SIGTERM #trap to catch interupts , deletes output and prompts user with exit condition
CURRENT=$(date) 
	
usage(){
	echo "usage $0 -t[tseconds] -n[count]"
} #this function will print out the correct usage when the shell is run incorrectly 

COUNT=5
TIME=1
echo " " > out.txt
until [[ $1 == -* ]]
do
   array+=( "$1" )
   shift
done

while getopts :t:n: option #getopts to pass arguments to the script
do 
	case "${option}"
	 in 
		t) TIME="$OPTARG";;
		n) COUNT="$OPTARG";;
		
		\?) case "$OPTARG" in
			t) echo " missing time parameter." ;;
			n) echo " missing count parameter." ;;
			\?) echo "Error: unknown option -$option";;  #catch all error message
			esac
			usage #print usage to screen
			exit 0
			;;
	esac 
done

echo "DATE: $CURRENT" > spy.txt
ps axo user,pid,comm >> spy.txt
echo " " 

echo " " > current.txt

for array in ${array[at symbol]} 
do
    grep "$array" spy.txt >> current.txt
done

head -1 spy.txt >> out.txt
for array in ${array[@]} 
do
    grep "$array" current.txt | sed "s/^/Started:/">> out.txt
done

let 'COUNT=COUNT-1'
mv current.txt last.txt

loop=1

while [ $COUNT -gt 0 ]; do
	echo "DATE: $CURRENT"> spy.txt
	
	ps axo user,pid,comm >> spy.txt  #run command ps -e to list all process and append it to thelog file
	
echo " "
	

echo " " > current.txt


for array in ${array[at symbol]} 
do
    grep "$array" spy.txt >> current.txt
done


head -1 spy.txt >> out.txt


awk 'NR==FNR{a[$1]++;next;}!($0 in a)' last.txt current.txt|sed "s/^/Ended:/" >> out.txt
	 	
awk 'NR==FNR{a[$1]++;next;}!($0 in a)' current.txt last.txt|sed "s/^/started:/" >> out.txt
	


		

mv current.txt last.txt
	let 'COUNT=COUNT-1' #count down mechanism for loop
	sleep $TIME  #argument to wait so many seconds between iterationso fo main loop
done

you run the command as such:
./spy [list of parameters] -t<seconds> -n <count>
The list of parameters is handled by sending the arguments into an array

Scripting is not my strong suit as you can tell

[atreyu]

the goal is to run the ps command and search the scans for comnmand line strings.

What is meant by "command line strings"? I guess this is what is in @array? Can you show an example of what that might be?

Then each time the loop runs the last scan and the first scan are compared and the results are output in a file.

What is the point of this? Can you show an example of what these first and last scans might look like?

I still don't understand what you are after, to be honest. I know you said you want to know if a script started or ended, but is there more to it than that?