I am having list of cron job functions.Each function run for certain period of time.Is there any way to find how long each cron function execute,Like time of start executing function and end time?
Expected output:
Cron tab start time: timestamp
cront tab end time: timestamp
Read crontab(5). A cron job is just a shell command or script. That shell could, for example, use logger(1) mixed with date(1) and time(1). See also time(7). See also GNU bash documentation.
A cron job could also be a GUILE script, or a Python one. See execve(2), fork(2) and other syscalls(2) which is called by crond
And cron is open source, so you are allowed to study its source code.... (e.g. of GNU mcron). Or use strace(1) on it to understand its behavior.
Consider reading Advanced Linux Programming and see Linux From Scratch.
For example, I am running thru cron a backup script starting with
#!/bin/bash
cd $HOME
renice -n +2 -p $$
ionice -c Best-effort -n +5 -p $$
tm=$(date +"backup-home+%Y-%b-%d-%Hh%M")
logger --id=$$ -t backup-home start $tm
sync
Related
When I run several background jobs, I need to get a runtime for the set of jobs.
I use the following example successfully:
$ sleep 10 &
$ time wait
real 0m9.74s
user 0m0.00s
sys 0m0.00s
However, if I try to format the output to seconds, I get the following error:
$ time -f %e wait
time: cannot run wait: No such file or directory
0.00
This only seems to happen with shell builtins. Is there a workaround for this?
The problem here is two-fold.
we don't know if you're using the bash (assuming you're using the centos default shell) built-in or the binary time command.
in either case wait is a bash built-in
Ways to deal with this:
/usr/bin/time -f %e bash -c wait
TIMEFORMAT="%pR" time bash -c wait
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 would like to run a specific script at a certain time (only once!). If I run it normally like this:
marc#Marc-Linux:~/tennis_betting_strategy1/wrappers$ Rscript write_csv2.R
It does work. I however would like to program it in a cronjob to run at 10:50 and therefore did the following:
50 10 11 05 * Rscript ~/csv_file/write_csv.R
This does not seem to work however. Any thoughts where I go wrong? These are the details of the cron package im
using:
PID COMMAND
1015 cron
My system time also checks out:
marc#Marc-Linux:~/tennis_betting_strategy1/wrappers$ date
wo mei 11 10:56:46 CEST 2016
There is a special tool for running commands only once - at.
With at you can schedule a command like this:
at 09:05 am today
at> enter you commands...
Note, you'll need the atd daemon running.
Your crontab entry looks okay, however. I'd suggest checking if the cron daemon is running(exact daemon name depends on the cron package; it could be cron, crond, or vixie-cron, for instance). One way to check if the daemon is running is to use the ps command, e.g.:
$ ps -C cron -o pid,args
PID COMMAND
306 /usr/sbin/cron
Some advices.
Read more about the PATH variable. Notice that it is set differently in interactive shells (see your ~/.bashrc) and in cron or at jobs. See also this about Rscript.
Replace your command by a shell script, e.g. in ~/bin/myrscriptjob.sh
That myrscriptjob.sh file should start with #!/bin/sh
Be sure to make that shell script executable:
chmod u+x ~/bin/myrscriptjob.sh
Add some logging in your shell script, near the start; either use logger(1) or at least some date(1) command suitably redirected, or even both:
#!/bin/sh
# file myrscriptjob.sh
/bin/date +"myrscriptjob starting %c %n" > /tmp/myrscriptjob.start
/usr/bin/logger -t myrscript job starting $$
/usr/local/bin/Rscript $HOME/csv_file/write_csv.R
in the last line above, replace /usr/local/bin/Rscript by the output of which Rscript done in some interactive terminal.
Notice that you should not use ~ (but replace them with $HOME when appropriate) in shell scripts.
Finally, use at to run your script once. If you want to run it periodically in a crontab job, give the absolute path, e.g.
5 09 11 05 * $HOME/bin/myrscriptjob.sh
and check in /tmp/myrscriptjob.start and in your system log if it has started successfully.
BTW, in your myrscriptjob.sh script, you might replace the first line #!/bin/sh with #!/bin/sh -vx (then the shell is verbose about execution, and cron or at will send you some email). See dash(1), bash(1), execve(2)
Use full path (started from /) for both Rscript and write_csv2.R. Check sample command as follows
/tmp/myscript/Rscript /tmp/myfile/write_csv2.R
Ensure you have execution permission of Rscript and write permission in folder where write_csv2.R will be created(/tmp/myfile)
I'm trying to make cron jobs or task schduler working, but I can not figure out why my script is not taken in consideration.
I'm trying to simply archive a folder with:
tar -cvf /volume1/NetBackup/Backups/Monday.tgz /volume1/NetBackup/Backups/ns3268116.ovh.net/
Each time the script starts working but cannot achieve the work. Either with task scheduler or crontab, a file Monday.tgz is created in folder /volume1/NetBackup/Backups/, but this file is only 1024 bytes.
Synology Cron is really fussy.
Here are my own personal notes for Synology DS413j, DSM 5.2:
Hand edit /etc/crontab as root, crontab -e isn't available
Ensure you use tabs not spaces to separate the columns
Your crontab changes may not survive a reboot if there are syntax problems
The who column in crontab may not be reliable. Use root in the who column and /bin/su -c '<command>' <username> to run as another other user
remember that it uses ash not bash so check for bashisms, e.g use >> /path/to/logfile 2>&1' not&>> /path/to/logfile`
It doesn't support 'MAILTO='
you need to restart crond synoservicectl --reload crond for the new crontab to take effect
You may try adding some diagnostics to it. For instance:
Add MAILTO into the crontab file (on top of crontab -e) to receive cron errors by email:
MAILTO=username#domain.com
Redirect output of your tar command to the file:
your command > ~/log.txt 2>&1
Check cron log and look for anomalies. For instance (it may depend on your configuration):
/var/log/cron.log
You may also try searching through /var/log/messages at the time of your cron job.
Is volume1 a resource on remote host? If yes, it is worth checking this part of the system.
I agree about the really nagging nature of Crontab on Synology Linux OSs.
I would certainly suggest to create de desired job as a .sh shell script and call it via CRON task inserted by using the GUI, as suggested here.
As for today (March 2017) is the best method I have found, since working with crontab via CLI is nearly a pain.
I want to get the details of the last run cron job. If the job is interrupted due to some internal problems, I want to re-run the cron job.
Note: I don't have superuser privilege.
You can see the date, time, user and command of previously executed cron jobs using:
grep CRON /var/log/syslog
This will show all cron jobs. If you only wanted to see jobs run by a certain user, you would use something like this:
grep CRON.*\(root\) /var/log/syslog
Note that cron logs at the start of a job so you may want to have lengthy jobs keep their own completion logs; if the system went down halfway through a job, it would still be in the log!
Edit: If you don't have root access, you will have to keep your own job logs. This can be done simply by tacking the following onto the end of your job command:
&& date > /home/user/last_completed
The file /home/user/last_completed would always contain the last date and time the job completed. You would use >> instead of > if you wanted to append completion dates to the file.
You could also achieve the same by putting your command in a small bash or sh script and have cron execute that file.
#!/bin/bash
[command]
date > /home/user/last_completed
The crontab for this would be:
* * * * * bash /path/to/script.bash
/var/log/cron contains cron job logs. But you need a root privilege to see.
CentOs,
sudo grep CRON /var/log/cron