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.??
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";
Related
I'm puzzled by this problem I'm having on Ubuntu 20.04 where cron is able to run a bash script but the overall outcome is different then when using the shell command.
I've look through all questions I could in here and on Google but couldn't find anyone that had the same problem.
Background:
I'm using Pushgateway to store metrics I'm generating through a bash script, and afterwards it's being imported automatically to Prometheus.
The end goal is to export a list of running processes, their CPU%, Mem% etc, similar to top command.
This is the bash script:
#!/bin/bash
z=$(top -n 1 -bi)
while read -r z
do
var=$var$(awk 'FNR>7{print "cpu_usage{process=\""$12"\", pid=\""$1"\"}", $9z} FNR>7{print "memory_usage{process=\""$12"\", pid=\""$1"\"}", $10z}')
done <<< "$z"
curl -X POST -H "Content-Type: text/plain" --data "$var
" http://localhost:9091/metrics/job/top/instance/machine
I used to have a version that used ps aux but then I found out that it only shows the average CPU% per process.
As you can see, the command I'm running is top -n 1 -bi which gives me a snapshot of active processes and their metrcis.
I'm using awk to format the data, and FNR>7 because I need to ignore the first 7 lines which is the summery presented by top.
The bash scrip is registered on /bin, /usr/bin and /usr/local/bin.
When checking http://localhost:9091/metrics, which is supposed to show me the information gathered, I'm getting this some of information when running the scrip using shell:
cpu_usage{instance="machine",job="top",pid="114468",process="php-fpm74"} 17.6
cpu_usage{instance="machine",job="top",pid="114483",process="php-fpm74"} 11.8
cpu_usage{instance="machine",job="top",pid="126305",process="ffmpeg"} 64.7
And this is the same information when cron is running the same script:
cpu_usage{instance="machine",job="top",pid="114483",process="php-fpm+"} 5
cpu_usage{instance="machine",job="top",pid="126305",process="ffmpeg"} 60
cpu_usage{instance="machine",job="top",pid="128777",process="php"} 15
So, for some reason, when I run it from cron it cuts the process name after 7 places.
I initially though it was related to the FNR>7 but even after changing it to 8 or 9 (and using exec bash to re-register the command) it gives the same results, also when I run it manually it works just fine.
Any help would be appreciated!!
I have some intermittent performance issues that I want to capture via perf top. The issue is intermittent, so I want to write a script that runs perf top when the issue is occurring so that I can save the data and view it at a later time.
I can't seem to figure out how to get perf top to put its output in a file, it seems to demand to be run interactively. Here is what I've tried so far:
# timeout 10 perf top --stdio -E 20 > 'perf-top'
This does not kill perf, just leaves it running in the background forever until I create another console session, find the PID, and kill it.
# timeout --signal=9 10 perf top --stdio -E 20 > 'perf-top'
This kills perf in the expected 10 seconds, but the output is not written to the file that I specified.
Is there some special way that this command needs to be run? It works if I run it from an interactive ssh session, but I'd really like to be able to run it from a script. I'm trying to put it into an ansible task with a few other metrics-gathering programs.
SIGKILL (9) isn't catchable, so it's impossible for perf to flush any buffered output.
Use any another signal so perf can clean up after receiving the signal and write output.
If the default SIGTERM doesn't work, then maybe try SIGHUP, SIGINT, or others.
timeout --signal=INT
timeout 10 perf top --stdio -E 20 > perf-top (with the default SIGTERM) works for me (as non-root) on my Arch Linux desktop. perf version 5.0.g1c163f4
I have multiple servers of Linux, where I need to test the performance of my program, here I want to output the system state when running programs. In script of linux, I use following to output:
top -b -d 5 > System.txt
iostat -d 8 > IO.txt
But unfortunately, only the system.txt can be produced, but there is no the IO.txt file, so that need to add some thing in script to make these two file exist together?
Use iostat command like this :-
iostat -d 8 1 > IO.txt.
In this 1 means the limit, how many time do you want to run the command get the result.
Basic information about my system: I have a music system where people can schedule songs to start and end at a specific time.
OS: Arch linux
It sets two crons at the moment. One lets say at 1.50 (start time with a command like "play etc") and another set at 3.20 (end time with a command like "end etc").
My setup works perfectly and i can end delete schedules etc etc but i now noticed an issue! If i set the above times and turn the system off (My system is a raspberry pi) and turn back on at lets say 2.00 and i missed the 1.50 deadline, the music doesnt start (obviously) and i want to try make it so no matter what time i turn it on within a range lets say: 1.50 - 3.20 it will start the play command. But it will run the command once!
I looked around and the commands i got was like:
0 1.50-3.20/2 * * * your_command.sh
But thats to run every 2 hours. I want it to run once only between these times?
Thanks!
You could add an additional cron job which starts a script on every reboot. For instance, you could add a line like this to your crontab:
#reboot /home/pi/startplayback.sh
Your startplayback.sh script should check if current time is within the desired period and run the desired command if it is. For example the code below will print PLAY! if the script is run between 1:50 and 3:20. You could replace echo 'PLAY!' by run WHATEVER
#!/bin/bash
current=$(date '+%H%M')
(( current=(10#$current) ))
((current > 150 && current < 320 )) && echo 'PLAY!'
P.S. Don't forget to make your script executable sudo chmod +x startplayback.sh
You might want to look at the at command and its utilities.
SYNOPSIS
at [-q queue] [-f file] [-mldbv] time
at [-q queue] [-f file] [-mldbv] -t [[CC]YY]MMDDhhmm[.SS]
at -c job [job ...]
at -l [job ...]
at -l -q queue
at -r job [job ...]
atq [-q queue] [-v]
atrm job [job ...]
batch [-q queue] [-f file] [-mv] [time]
at is good for scheduling one time jobs to be run at some point in the future. It maintains a queue of these jobs, so you can use it to schedule things with a great variety of different time specifications.
Cron is in my opinion a scheduler for jobs that are to be repeated over and over.
So a quick and dirty example for you:
echo 'ls -lathF' | at now + 1 minute
As expected you will see a job to be run in one minute. Try atq to see the list of jobs.
When the job is done, output will be mailed to your user by default.
I solved the issue by creating a PHP file and load the page on reboot then do its work and redirect back to such and such.
I have the following bash file which should create a screen, go to a directory and then start a node script:
screen -S shared // 1
cd /home/nodejsapp // 2
node start.js app.js // 3
The problem is, after executing 1, I indeed see the screen 'shared', but 2 & 3 will execute on the previous terminal, not on the screen 'shared'.
How can I achieve that commands 2 and 3 will be executed on the current screen?
You may create a detached screen and then send commands to it. For example:
screen -d -m -S shared
screen -S shared -X -p 0 stuff $'cd /home/nodejsapp\n'
screen -S shared -X -p 0 stuff $'node start.js app.js\n'
If you need to attach to the screen session afterwards, then you can add one more line:
screen -S shared -r
See screen's manual for more details:
screen options
screen commands
You could run a "server" as the program within screen, which reads commands to execute from the pseudoterminal which the "tty" program identifies. For instance, as I'm writing this, tty says (inside screen)
/dev/pts/2
and I can write to it by
date >/dev/pts/2
On the server side, the script would read line-by-line in a loop from the same device. (On some other systems, there are differently-named
devices for each side of the pseudoterminal).
That only needs a script which starts by getting the output of "tty", writing that to a file (which a corresponding client would know of), and then the client would read commands (whether from the keyboard or a file), write them to the server via the pty device.
That's doable with just a couple of shell scripts (a little more lengthy though than the usual answer here).