Debian – How to make Debian run m python script at startup

Put your script in /etc/network/if-up.d and make it executable. It will be automatically run each time a network interface comes up.

To make it do work only the first time it is run on every boot, have it check for existence of a flag file which you create after the first time. Example:

#!/bin/sh

FLAGFILE=/var/run/work-was-already-done

case "$IFACE" in
    lo)
        # The loopback interface does not count.
        # only run when some other interface comes up
        exit 0
        ;;
    *)
        ;;
esac

if [ -e $FLAGFILE ]; then
    exit 0
else
    touch $FLAGFILE
fi

: here, do the real work.

If you've done everything such as chmod +x /etc/rc.local then your command is running, it's just not getting logged anywhere that you can see it.

Example

This is my /etc/rc.local:

$ cat /etc/rc.local
#!/bin/bash
touch /var/lock/subsys/local
echo "hickory stick"

Here I've used the modified Bash which logs to syslog which I discussed in this other U&L Q&A titled: Sending bash history to syslog.

When my system boots I see the following message getting logged via Bash:

/var/log/bash-log/127.0.0.1.log:2018-07-24T22:04:24.609094-04:00 centos7 rc.local: hickory stick

But no where else. To get this to log to syslog/rsyslog you typically can use the logger command to do so:

$ logger hi

You can then see it in your /var/log/messages or /var/log/syslog or journal -xef. Here I'm using journald:

$ journalctl -xef
Jul 24 20:23:04 centos7 bash[1629]: HISTORY: PID=1629 UID=0 USER=root CMD=man logger
Jul 24 20:23:24 centos7 bash[1629]: HISTORY: PID=1629 UID=0 USER=root CMD=logger hi
Jul 24 20:23:24 centos7 vagrant[1811]: hi

You should be able to use logger to capture output from commands in scripts like so:

$ cat /etc/rc.local
#!/bin/bash
touch /var/lock/subsys/local
echo "hickory stick" | logger

Now when we reboot:

$ journalctl -xef
...
Jul 24 20:31:41 centos7 bash[1629]: HISTORY: PID=1629 UID=0 USER=root CMD=journalctl -xe
Jul 24 22:24:00 centos7 logger[1286]: hickory stick
Jul 24 22:24:00 centos7 sshd[1270]: Server listening on 0.0.0.0 port 22.
Jul 24 22:24:00 centos7 sshd[1270]: Server listening on :: port 22.
Jul 24 22:24:00 centos7 systemd[1]: Starting Permit User Sessions...

We see our message there via logger that we added to /etc/rc.local.

Extra info

logger is a pretty useful and you can have it log to a file instead of via the -f switch, you can also control the tag that shows up in the logs with the -t switch.

$ logger -t "smurfs" hi
$ journalctl -xe | grep smurfs
Jul 24 20:38:24 centos7 smurfs[1764]: hi

References

• Shell scripting: Write message to a syslog / log file