I want to make a loop in CentOS SSH Terminal where it loops over certain commands. For example:
zmap -p22 -o mfu.txt -B100M -N 250000
Waits until that's finished
chmod 777 *
./update 1500
Stops task after 25 mins
perl wget.pl vuln.txt
repeat the process
Do you want to parallelize step 1? Use parallel.
Step 3../update is very broad. Do you want to update dataset/underlying programs? Dump output?
For step 3.repeating and step 5.repeat you could use something like
How to have a bash script loop until a specific time
For step 5, do you want to repeat the process during a specific time (like step 3), or for a number of iterations ? For the second option you can do something like (with N iterations):
for i in $(seq 1 N); do execute steps 1 to 4; done
Related
Basic information about my system: I have a music system where people can schedule songs to start and end at a specific time.
OS: Arch linux
It sets two crons at the moment. One lets say at 1.50 (start time with a command like "play etc") and another set at 3.20 (end time with a command like "end etc").
My setup works perfectly and i can end delete schedules etc etc but i now noticed an issue! If i set the above times and turn the system off (My system is a raspberry pi) and turn back on at lets say 2.00 and i missed the 1.50 deadline, the music doesnt start (obviously) and i want to try make it so no matter what time i turn it on within a range lets say: 1.50 - 3.20 it will start the play command. But it will run the command once!
I looked around and the commands i got was like:
0 1.50-3.20/2 * * * your_command.sh
But thats to run every 2 hours. I want it to run once only between these times?
Thanks!
You could add an additional cron job which starts a script on every reboot. For instance, you could add a line like this to your crontab:
#reboot /home/pi/startplayback.sh
Your startplayback.sh script should check if current time is within the desired period and run the desired command if it is. For example the code below will print PLAY! if the script is run between 1:50 and 3:20. You could replace echo 'PLAY!' by run WHATEVER
#!/bin/bash
current=$(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 need some help in writing a Linux script that do the following:
command 1
command 2
wait 10 minutes
command 3
command 4
and this script should run automatically at specific time for example 4 am...
Thank in advance
You can create a script.sh like:
#!/bin/bash
command 1
command 2
sleep 600 # 600 seconds = 10 min
command 3
command 4
And then create a cronjob:
0 4 * * * /bin/bash /path/to/script.sh
You can see more info of cron in https://stackoverflow.com/tags/cron/info
if you want the job to run once at a future time, instead of cron use at
at 4am tomorrow <<END
command 1
command 2
sleep 600
command 3
command 4
END
One of the advantages of at is that it will execute the commands using your current environment. The limited environment provided by cron is a cause of confusion for many people.
I have seven licenses of a particular software. Therefore, I want to start 7 jobs simultaneously. I can do that using '&'. Now, 'wait' command waits till the end of all of those 7 processes to be finished to spawn the next 7. Now, I would like to write the shell script where after I start the first seven, as and when a job gets completed I would like to start another. This is because some of those 7 jobs might take very long while some others get over really quickly. I don't want to waste time waiting for all of them to finish. Is there a way to do this in linux? Could you please help me?
Thanks.
GNU parallel is the way to go. It is designed for launching multiples instances of a same command, each with a different argument retrieved either from stdin or an external file.
Let's say your licensed script is called myScript, each instance having the same options --arg1 --arg2 and taking a variable parameter --argVariable for each instance spawned, those parameters being stored in file myParameters :
cat myParameters | parallel -halt 1 --jobs 7 ./myScript --arg1 --argVariable {} --arg2
Explanations :
-halt 1 tells parallel to halt all jobs if one fails
--jobs 7 will launch 7 instances of myScript
On a debian-based linux system, you can install parallel using :
sudo apt-get install parallel
As a bonus, if your licenses allow it, you can even tell parallel to launch these 7 instances amongst multiple computers.
You could check how many are currently running and start more if you have less than 7:
while true; do
if [ "`ps ax -o comm | grep process-name | wc -l`" -lt 7 ]; then
process-name &
fi
sleep 1
done
Write two scripts. One which restarts a job everytime it is finished and one that starts 7 times the first script.
Like:
script1:
./script2 job1
...
./script2 job7
and
script2:
while(...)
./jobX
I found a fairly good solution using make, which is a part of the standard distributions. See here
So, I was wondering if there was a bash command that lets me fork a process which sleeps for several seconds, then executes a command.
Here's an example:
sleep 30 'echo executing...' &
^This doesn't actually work (because the sleep command only takes the time argument), but is there something that could do something like this? So, basically, a sleep command that takes a time argument and something to execute when the interval is completed? I want to be able to fork it into a different process then continue processing the shell script.
Also, I know I could write a simple script that does this, but due to some restraints to the situation (I'm actually passing this through a ssh call), I'd rather not do that.
You can do
(sleep 30 && command ...)&
Using && is safer than ; because it ensures that command ... will run only if the sleep timer expires.
You can invoke another shell in the background and make it do what you want:
bash -c 'sleep 30; do-whatever-else' &
The default interval for sleep is in seconds, so the above would sleep for 30 seconds. You can specify other intervals like: 30m for 30 minutes, or 1h for 1 hour, or 3d for 3 days.
I want to create a script that, after knowing that my machine has been turned on for at least 7h, it does something.
Is this possible? Is there a system variable or something like that that shows me the last time the machine was turned on?
The following command placed in /etc/rc.local:
echo 'touch /tmp/test' | at -t $(date -d "+7 hours" +%m%d%H%M)
will create a job that will run a touch /tmp/test in seven hours.
To protect against frequent reboots and prevent adding multiple jobs you could use one at queue exclusively for this type of jobs (e.g. c queue). Adding -q c to the list of at parameters will place the job in the c queue. Before adding new job you can delete all jobs from c queue:
for job in $(atq -q c | sed 's/[ \t].*//'); do atrm $job; done
You can parse the output of uptime I suppose.
As Pavel and thkala point out below, this is not a robust solution. See their comments!
The uptime command shows you how long the system has been running.
To accomplish your task, you can make a script that first does sleep 25200 (25200 seconds = 7 hours), and then does something useful. Have this script run at startup, for example by adding it to /etc/rc.local. This is a better idea than polling the uptime command to see if the machine has been up for 7 hours (which is comparable to a kid in the backseat of a car asking "are we there yet?" :-))
Just wait for uptime to equal seven hours.
http://linux.die.net/man/1/uptime
I don't know if this is what you are looking for, but uptime command will give you for how many computer was running since last reboot.
$ cut -d ' ' -f 1 </proc/uptime
This will give you the current system uptime in seconds, in floating point format.
The following could be used in a bash script:
if [[ "$(cut -d . -f 1 </proc/uptime)" -gt "$(($HOURS * 3600))" ]]; then
...
fi
Add the following to your crontab:
#reboot sleep 7h; /path/to/job
Either /etc/crontab, /etc/cron.d/, or your users crontab, depending on whether you want to run it as root or the user -- don't forget to put "root" after "#reboot" if you put it in /etc/crontab or cron.d
This has the benefit that if you reboot multiple times, the jobs get cancelled at shut down, so you won't get a bunch of them stacking up if you reboot several times within 7 hours. The "#reboot" time specification triggers the job to be run once when the system is rebooted. "sleep 7h;" waits for 7 hours before running "/path/to/job".