Crontab fails to run a shell

zackryderrrr · 10-07-2020, 02:20 PM

there's a command to start up a service which is

Code:

su -s /bin/bash nuance -c '$JAVA_HOME/bin/java -Dlog4j.configurationFile=$NLPS_HOME/config/log4j2.xml -jar $NLPS_HOME/lib/nlps.jar --spring.config.location=$NLPS_HOME/config/,$NUANCE_DATA_DIR/system/config/User-nlps01.properties  watcher.RestartOnFailure=FALSE watcher.SendAlarmsToWatcher=FALSE > /dev/null 2>&1 &'

I want this command to run at startup in my rhel 7 linux. So I tried crontab, which is @reboot sh /execute/nlp.sh

But it doesn't work, I don't know why. Please tell me what I'm doing wrong I'm so stuck Inside nlp.sh:

Code:

#!/bin/bash
/bin/su -s /bin/bash nuance -c '$JAVA_HOME/bin/java -Dlog4j.configurationFile=$NLPS_HOME/config/log4j2.xml -jar $NLPS_HOME/lib/nlps.jar --spring.config.location=$NLPS_HOME/config/,$NUANCE_DATA_DIR/system/config/User-nlps01.properties  watcher.RestartOnFailure=FALSE watcher.SendAlarmsToWatcher=FALSE > /dev/null 2>&1 &'

frankbell · 10-07-2020, 07:28 PM

Please surround the code with "code" tags, which become available when you click the "Go Advanced" button beneath the compose/edit post window.

It will make the code much easier to read and critique.

scasey · 10-07-2020, 07:34 PM

A cron job wouldn't typically have those environment variables set. cron doesn't have the same environment as your user, unless you set it up...typically within the script itself...which means you could just code the actual paths in the command(s)

But yes, please edit your OP to put the code in code tags. Very hard to see what you're actually doing without them. There's a how-to link in my sig

sgosnell · 10-07-2020, 08:14 PM

The su -s won't work because it requires a password to be entered. Delete that and run the rest from root's crontab. I have no idea what the rest does, so I can't say if it will work as entered.

tofino_surfer · 10-07-2020, 09:28 PM

If you are trying to start a service at boot time you should create a systemd service and add it to your default target. Using crontab for this is the wrong way. Crontab is for regularly scheduled operations such as backups. It is not for starting services.

pan64 · 10-08-2020, 01:33 AM

additionally would be better to write a script for that command instead of putting it directly into crontab.
replace redirections (instead of /dev/null into a logfile) to see what's wrong.

But as it was mentioned: crontab uses a different environment, so probably your script is unable to run from cron. Also a service should be configured instead.

lpwevers · 10-08-2020, 01:57 AM

As said by @tofino_server, try creating a systemd service. Something like this should work:

Code:

[Unit]
Description=<Name of your service>
After=network.target

[Service]
User=nuance
Group=users
PIDFile=/var/run/<your pid>.pid
Environment=JAVA_HOME=<path to java home>
Environment=NLPS_HOME=<path to NLPS home>
Environment=NUANCE_DATA_DIR=<path to data dir>
WorkingDirectory=${NLPS_HOME}
ExecStart= ${JAVA_HOME}/bin/java -Dlog4j.configurationFile=${NLPS_HOME}/config/log4j2.xml -jar ${NLPS_HOME}/lib/nlps.jar --spring.config.location=${NLPS_HOME}/config/,${NUANCE_DATA_DIR}/system/config/User-nlps01.properties watcher.RestartOnFailure=FALSE watcher.SendAlarmsToWatcher=FALSE > /dev/null 2>&1
ExecReload=/bin/kill -s HUP $MAINPID
ExecStop=/bin/kill $MAINPID
KillSignal=SIGQUIT
TimeoutStopSec=60
KillMode=process

[Install]
WantedBy=multi-user.target

Save it in /etc/systemd/system/nlps.service. Then try starting it with something like:

Code:

systemctl start nlps

If that works, enable the service so it starts at runtime:

Code:

systemctl enable nlps

If at first it doesn't work and you need to change your service file, don't forget to run

Code:

systemctl daemon-reload

before trying to start the service again.

zackryderrrr · 10-08-2020, 01:32 PM

Yes, I've edited my post with "code". First thank you guys for the responses, much appreciated as other forums didn't even respond. And yeah crontab is a bad option I guess and I even included all the environment variables like "export NLPS_HOME=/path" also I gave full paths without '$ path' and the shell script works fine. But I want this to be executed at the startup. If the shell script works why can't crontab or even a simple systemd service doesn't execute properly? Please enlighten me guys!

zackryderrrr · 10-08-2020, 01:37 PM

Quote:

Originally Posted by lpwevers

As said by @tofino_server, try creating a systemd service. Something like this should work:

Code:

[Unit]
Description=<Name of your service>
After=network.target

[Service]
User=nuance
Group=users
PIDFile=/var/run/<your pid>.pid
Environment=JAVA_HOME=<path to java home>
Environment=NLPS_HOME=<path to NLPS home>
Environment=NUANCE_DATA_DIR=<path to data dir>
WorkingDirectory=${NLPS_HOME}
ExecStart= ${JAVA_HOME}/bin/java -Dlog4j.configurationFile=${NLPS_HOME}/config/log4j2.xml -jar ${NLPS_HOME}/lib/nlps.jar --spring.config.location=${NLPS_HOME}/config/,${NUANCE_DATA_DIR}/system/config/User-nlps01.properties watcher.RestartOnFailure=FALSE watcher.SendAlarmsToWatcher=FALSE > /dev/null 2>&1
ExecReload=/bin/kill -s HUP $MAINPID
ExecStop=/bin/kill $MAINPID
KillSignal=SIGQUIT
TimeoutStopSec=60
KillMode=process

[Install]
WantedBy=multi-user.target

Save it in /etc/systemd/system/nlps.service. Then try starting it with something like:

Code:

systemctl start nlps

If that works, enable the service so it starts at runtime:

Code:

systemctl enable nlps

If at first it doesn't work and you need to change your service file, don't forget to run

Code:

systemctl daemon-reload

before trying to start the service again.

Yes I tried your systemd service but it fails. The spring breaks while starting this as a service, it really looks like a neat service but it fails.

sgosnell · 10-08-2020, 02:15 PM

You can put the script in /etc/rc.local and it will run at system startup. You will need to edit it to make a proper script, but it shouldn't be that hard.

tofino_surfer · 10-09-2020, 12:36 AM

Quote:

You can put the script in /etc/rc.local and it will run at system startup. You will need to edit it to make a proper script, but it shouldn't be that hard.

You may not have heard but using /etc/rc.local does not work on systemd installations. The file /etc/rc.local does not even exist on modern systemd Linuxes. You need to create a systemd service to call /etc/rc.local at boot time on systemd installations as well as create the /etc/rc.local bash script file itself and make it executable with chmod.

https://www.linuxbabe.com/linux-serv...l-with-systemd

Given this fact the proper way to do what the OP needs is with a systemd service as lpwevers showed.

Since Debian is also a systemd distro your advice would not work there either.