Running 'top' command of linux for few minutes and then come out of system command in perl

Question

I am new to Perl. I am working on a web UI where I have to give CPU and memory monitoring data, so I am using top and gnuplot command. I am able to do it through my terminal. but when I am executing same commands with a perl script its not working. The problem I am having is that whenever I am executing top command in my terminal than I have to wait for few minutes and then I have to plot it using GNUPLOT but when I am doing the same work using system command in perl I am unable to give that delay.

Here is what I am doing

system "top -p 1758 -b -d5 | tee -a stats.log";
system "./top_stats.sh -f stats.log"

Here 1758 is the app ID whose top data I have to monitor and stats.log file is the one where I am saving logs and then using this stats.log file as input to top_stats.sh script I am plotting graphs. This top_stats.sh script takes the log file and uses gnuplot to plot data

Now the problem is whenever I am executing this first system command in terminal I have to wait for some time say 2 to 3 minutes to have ample number of data points and then I have to press Ctrl+C to come out of top command and then run the script. but here as soon as this first system command is encountered it is executed and then next command is executed without any delay so I am not getting any data points to plot the graph. Is there any way I can execute my first command and wait for 3 minutes without coming out of system command and then execute the next command.??

Answer 1

Is there any way I can execute my first command and wait for 3 minutes without coming out of system command and then execute the next command.??

Why not specify the number of iteration for top . So your command will rougly run for (N-1)*5 seconsds. 37 iterations with an interval of 5 seconds are going to take 36*5 seconds:

system "top -p 1758 -b -d5 -n37 | tee -a stats.log && ./top_stats.sh -f stats.log";