Alternative to #reboot for busybox crond? - cron

I'm trying to run a script at startup using busybox, but I've read that #reboot isn't supported with my version of cron. I need to use cron for this rather than running the script some other way. Is there an alternative solution to getting it to run at startup with crond and crontab?

#reboot can be implemented in Busybox by using /etc/init.d/local (& placing the scripts in /etc/local.d).
It can also be done by altering /etc/init.d/crond.

Related

Synology - Cron job

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.

crontab #reboot does not execute bash script when server is rebooted

I'm using #reboot ~/www/example.com/bin/server in my user's crontab...but when I reboot the server, the web server (this script) does not come up. (script works fine from command line).
My guess is the /home/user directory has not been mounted yet...does anyone know if its possible to get a script to run out of a home directory using this crontab #reboot method?
If you think /home/user hasn't been mounted (or some required systems aren't running) yet, in your crontab line, you can always wait before executing a command like:
#reboot sleep 60; /home/user/www/example.com/bin/server
It should definitely be due to the environment scenarios as given in comments. Try the following and check once by doing a reboot
#reboot (date > /tmp/date-check.txt)
To be sure cron is able to run the jobs.
My problem was that the crontab did not have a full environment. I made the script it was pointing to source my .bashrc.
#reboot /home/user/www/example.com/bin/server
./server does . /home/user/.bashrc to get a working environment.
In Ubuntu if you are using the Home Directory Encryption feature turned on then #reboot in your crontab file won't work as the file system is still encrypted when the system is starting up and cron runs its #reboot jobs.
Your options are to place your files in an unencrypted location (/usr/local/bin or something?) or disable Home Directory encryption on your home directory.

Starting tty.js on Boot

I'm trying to start a tty.js shell on boot which is pretty easy with a cron job on boot, but it doesn't start the environment correctly. It doesn't have the right $PATH and such. It is not executing the right scripts like /etc/environment, ~/.bashrc, etc. Is there a way to start tty.js on boot with the same environment when you login.
On Gentoo at least, you set up the environment explicitly using the source /etc/profile command. It resets environment variables and the likes. Give that a try.
For Ubuntu cron jobs at boot and upstart do not load /etc/environment because that is normally done by pam_env.so when you login. However, su does the proper loading of /etc/environment and /etc/profile. So in a cron job at boot or in upstart you could do something like:
exec su username -c "/home/username/bin/tty.js 1> /home/username/tty.log 2> /home/username/tty.log &"

How to run a shell script at startup

On an Amazon S3 Linux instance, I have two scripts called start_my_app and stop_my_app which start and stop forever (which in turn runs my Node.js application). I use these scripts to manually start and stop my Node.js application. So far so good.
My problem: I also want to set it up such that start_my_app is run whenever the system boots up. I know that I need to add a file inside init.d and I know how to symlink it to the proper directory within rc.d, but I can't figure out what actually needs to go inside the file that I place in init.d. I'm thinking it should be just one line, like, start_my_app, but that hasn't been working for me.
First create your startup script # /home/user/startup.sh, and make it executable
chmod +x /home/user/startup.sh
Then set a crontab for it:
$ crontab -e
#reboot /home/user/startup.sh
Now your your startup.sh script will run at every start.
The file you put in /etc/init.d/ have to be set to executable with:
chmod +x /etc/init.d/start_my_app
As pointed out by #meetamit, if it still does not run you might have to create a symbolic link to the file in /etc/rc.d/
ln -s /etc/init.d/start_my_app /etc/rc.d/
Please note that on the latest versions of Debian, this will not work as your script will have to be LSB compliant (provide at least the following actions: start, stop, restart, force-reload, and status):
https://wiki.debian.org/LSBInitScripts
As a note, you should always use the absolute path to files in your scripts instead of the relative one, it may solve unexpected issues:
/var/myscripts/start_my_app
Finally, make sure that you included the shebang on top of the file:
#!/bin/sh
A simple approach is to add a line in /etc/rc.local :
/PATH/TO/MY_APP &
or if you want to run the command as a special user :
su - USER_FOOBAR -c /PATH/TO/MY_APP &
(the trailing ampersand backgrounds the process and allows the rc.local to continue executing)
If you want a full init script, debian distro have a template file, so :
cp /etc/init.d/skeleton /etc/init.d/your_app
and adapt it a bit.
This is the way I do it on Red Hat Linux systems.
Put your script in /etc/init.d, owned by root and executable. At the top of the script, you can give a directive for chkconfig. Example, the following script is used to start a Java application as user oracle.
The name of the script is /etc/init.d/apex
#!/bin/bash
# chkconfig: 345 99 10
# Description: auto start apex listener
#
case "$1" in
'start')
su - oracle -c "cd /opt/apex ; java -jar apex.war > logs/apex.log 2>logs/apex_error.log &";;
'stop')
echo "put something to shutdown or kill the process here";;
esac
This says that the script must run at levels 3, 4, and 5, and the priority for start/stop is 99 and 10.
Then, as user root you can use chkconfig to enable or disable the script at startup:
chkconfig --list apex
chkconfig --add apex
And you can use service start/stop apex.
Enter cron using sudo:
sudo crontab -e
Add a command to run upon start up, in this case a script:
#reboot sh /home/user/test.sh
Save:
Press ESC then :x to save and exit, or hit ESC then ZZ (that's shift+zz)
Test Test Test:
Run your test script without cron to make sure it actually works.
Make sure you saved your command in cron, use sudo crontab -e
Reboot the server to confirm it all works sudo #reboot
Just have a line added to your crontab..
Make sure the file is executable:
chmod +x /path_to_you_file/your_file
To edit crontab file:
crontab -e
Line you have to add:
#reboot /path_to_you_file/your_file
That simple!
Another option is to have an #reboot command in your crontab.
Not every version of cron supports this, but if your instance is based on the Amazon Linux AMI then it will work.
Edit the rc.local file using nano or gedit editor and add your scripts in it. File path could be /etc/rc.local or /etc/rc.d/rc.local.
sudo nano /etc/rc.local
This is the edit:
#!/bin/sh
/path-to-your-script/your-scipt-name.sh
once done press ctrl+o to update, pressEnter then ctrl+x.
Make the file executable.
sudo chmod 755 /etc/rc.local
Then initiate the rc-local service to run script during boot.
sudo systemctl start rc-local
You can do it :
chmod +x PATH_TO_YOUR_SCRIPT/start_my_app
then use this command
update-rc.d start_my_app defaults 100
Please see this page on Cyberciti.
Many answers on starting something at boot, but often you want to start it just a little later, because your script depends on e.g. networking. Use at to just add this delay, e.g.:
at now + 1 min -f /path/yourscript
You may add this in /etc/rc.local, but also in cron like:
# crontab -e
#reboot at now + 1 min -f /path/yourscript
Isn't it fun to combine cron and at? Info is in the man page man at.
As for the comments that #reboot may not be widely supported, just try it. I found out that /etc/rc.local has become obsolete on distros that support systemd, such as ubuntu and raspbian.
The absolute easiest method if all you want to run is a simple script, (or anything) is if you have a gui to use system > preferences then startup apps.
just browse to the script you want and there you go. (make script executable)
This simple solution worked for me on an Amazon Linux instance running CentOS.
Edit your /etc/rc.d/rc.local file and put the command there. It is mentioned in this file that it will be executed after all other init scripts. So be careful in that regards. This is how the file looks for me currently.. Last line is the name of my script.
Create your own /init executable
This is not what you want, but it is fun!
Just pick an arbitrary executable file, even a shell script, and boot the kernel with the command line parameter:
init=/path/to/myinit
Towards the end of boot, the Linux kernel runs the first userspace executable at the given path.
Several projects provide popular init executables used by major distros, e.g. systemd, and in most distros init will fork a bunch of processes used in normal system operation.
But we can hijack /init it to run our own minimal scripts to better understand our system.
Here is a minimal reproducible setup: https://github.com/cirosantilli/linux-kernel-module-cheat/tree/f96d4d55c9caa7c0862991025e1291c48c33e3d9/README.md#custom-init
I refered to this blog, always sound a good choice
https://blog.xyzio.com/2016/06/14/setting-up-a-golang-website-to-autorun-on-ubuntu-using-systemd/
vim /lib/systemd/system/gosite.service
Description=A simple go website
ConditionPathExists=/home/user/bin/gosite
[Service]
Restart=always
RestartSec=3
ExecStart=/home/user/bin/gosite
[Install]
WantedBy=multi-user.target
systemctl enable gosite.service
multi ways to finish it:
crontab
rc.local
init.d
systemd
For Debian 9 see https://askubuntu.com/questions/228304/how-do-i-run-a-script-at-start-up. It is helped me. Short version for Debian 9:
add commands (as root) to /etc/rc.local
/path_to_file/filename.sh || exit 1 # Added by me
exit 0
Probably, /path_to_file/filename.sh should be executable (I think so).
In Lubuntu I had to deal with the opposite situation. Skype start running after booting and I found in ~/.config/autostart/ the file skypeforlinux.desktop. The content of the file is as follows:
[Desktop Entry]
Name=Skype for Linux
Comment=Skype Internet Telephony
Exec=/usr/bin/skypeforlinux
Icon=skypeforlinux
Terminal=false
Type=Application
StartupNotify=false
X-GNOME-Autostart-enabled=true
Deleting this file helped me.
Here is a simpler method!
First: write a shell script and save it a .sh
here is an example
#!/bin/bash
Icoff='/home/akbar/keyboardONOFF/icon/Dt6hQ.png'
id=13
fconfig=".keyboard"
echo "disabled" > $fconfig
xinput float $id
notify-send -i $Icoff "Internal Keyboard disabled";
this script will disable the internal keyboard at startup.
Second: Open the application " Startup Application Preferences"
enter image description here
enter image description here
Third: click Add.
fourth: in the NAME section give a name.
fifth: In the command section browse to your .sh .
sixth: edit your command section to:
bash <space> path/to/file/<filename>.sh <space> --start
seventh: click Add. Thats it! Finished!
Now confirm by rebooting your pc.
cheers!
Add your script to /etc/init.d/ directory
Update your rc run-levels:
$ update-rc.d myScript.sh defaults NN where NN is the order in which it should be executed. 99 for example will mean it would be run after 98 and before 100.
Painless, easiest and the most universal method is simply
executing it with ~.bash_profile or ~.profile (if you don't have bash_profile file).
Just add the execution command at the bottom of that file and it will be executed when system started.
I have this one at the bottom an example;
~\Desktop\sound_fixer.sh
Working with Python 3 microservices or shell; using Ubuntu Server 18.04 (Bionic Beaver) or Ubuntu 19.10 (Eoan Ermine) or Ubuntu 18.10 (Cosmic Cuttlefish) I always do like these steps, and it worked always too:
Creating a microservice called p example "brain_microservice1.service" in my case:
$ nano /lib/systemd/system/brain_microservice1.service
Inside this new service that you are in:
[Unit]
Description=brain_microservice_1
After=multi-user.target
[Service]
Type=simple
ExecStart=/usr/bin/python3.7 /root/scriptsPython/RUN_SERVICES/microservices /microservice_1.py -k start -DFOREGROUND
ExecStop=/usr/bin/python3.7 /root/scriptsPython/RUN_SERVICES/microservices/microservice_1.py -k graceful-stop
ExecReload=/usr/bin/python3.7 /root/scriptsPython/RUN_SERVICES/microservices/microservice_1.py -k graceful
PrivateTmp=true
LimitNOFILE=infinity
KillMode=mixed
Restart=on-failure
RestartSec=5s
[Install]
WantedBy=multi-user.target
Give the permissions:
$ chmod -X /lib/systemd/system/brain_microservice*
$ chmod -R 775 /lib/systemd/system/brain_microservice*
Give the execution permission then:
$ systemctl daemon-reload
Enable then, this will make then always start on startup
$ systemctl enable brain_microservice1.service
Then you can test it;
$ sudo reboot now
Finish = SUCCESS!!
This can be done with the same body script to run shell, react ... database startup script ... any kind os code ... hope this help u...
...
For some people, this will work:
You could simply add the following command into System → Preferences → Startup Applications:
bash /full/path/to/your/script.sh

How to use crond instead of atd?

I have an embedded device running busybox. The device has crond installed and running, but has no atd daemon. I need to schedule task to run at a given time (just once, not periodically). I know, that the "kosher" way is to use at command, but I unfortunately don't have one. So, how can I use cron as a workaround?
You can set up the cron to run your script, and when it succeeds, the script should just comment out or remove the cron entry.

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