Shellcmd that doesn't block (non-blocking) and allows boot to continue

[luckman212]

I'm running 22.01 dev snapshots on a 6100 and wanted to use the Shellcmd package to execute a script at boot that fixes the LEDs. So it needs to wait ~30s for the boot to complete otherwise the setting gets trampled by the led_normalize() at the bootup complete stage of the main rc script.

I tried various invocations like

(sleep 30 ; echo 0 >/dev/led/blue3; )&
#or
/bin/sh -c 'sleep 30; echo 0 >/dev/led/blue3' &
#or
/root/my-led-setting-script.sh & 

None of those worked- all of them blocked and halted the boot until the script finished. Is this a limitation of the way the Shellcmd package (or php?) calls out to the shell? I ended up punting and using a script in /usr/local/etc/rc.d/ but even the Netgate docs recommend not doing that.

I searched and didn't find much about this, except for r/PFSENSE: Non-blocking shellcmd? —which didn't get a definitive answer.

[Gertjan]

@luckman212

See here.

Now you know the PHP exec() is used, you can, look her https://www.php.net/manual/fr/function.exec.php and try out what has been proposed over there.

@luckman212 said in Shellcmd that doesn't block (non-blocking) and allows boot to continue:

a script in /usr/local/etc/rc.d/ but even the Netgate docs recommend not doing that.

But they mentioned it ;)
That method give you the most control.

[luckman212]

@gertjan Thanks. I'll paste the important bit below to save anyone else a click:

so I assume maybe the fix would be to make the shellcmd something like /bin/sh -c 'sleep 30; echo 0 >/dev/led/blue3' >/dev/null

[luckman212]

Still can't get it to work

If I enter an interactive php shell with php -a and then run

exec("/bin/sh -c '/bin/sleep 5; echo 1 >/dev/led/amber3' >/dev/null &");

it does return control immediately and also turns on the LED after 5s. So that works.

But, the same command in the Shellcmd package doesn't work. I thought maybe it was because the string gets escaped e.g. > becomes >, but when I tested a little patch, adding htmlspecialchars_decode() inside the exec() it did not change anything...

[Gertjan]

@luckman212

What about placing the commands in a script file "test.sh" :

#!/usr/local/bin/bash
exec("/bin/sh -c '/bin/sleep 5; echo 1 >/dev/led/amber3' >/dev/null &");

Make the script file executable with

chmod +x test.sh

and then use

/root/test3.sh

as the early start command ?

[luckman212]

@gertjan The top code snippet you wrote there has the wrong shebang (exec() is php, not bash). But aside from that, this is basically what I've done—put the commands in a script at /usr/local/etc/rc.d/

The problem with that is it requires manually copying the scripts, making sure they are backed up/restored etc. It would be nice to be able to use Shellcmd since everything is contained within the config.xml...

[Gertjan]

@luckman212 said in Shellcmd that doesn't block (non-blocking) and allows boot to continue:

The top code snippet you wrote there has the wrong shebang (exec() is php, not bash).

The PHP exec() function executes a command.
Not a binary command like 'sleep' or '/bin/sleep' (the command + path) but a command shell script file.
The 'language interpreter' of the script files is .... not PHP. It's bash. So the sheban is bash.

@luckman212 said in Shellcmd that doesn't block (non-blocking) and allows boot to continue:

The problem with that is it requires manually copying the scripts, making sure they are backed up/restored etc. It would be nice to be able to use Shellcmd since everything is contained within the config.xml...

I understand. It would be best if everything was self contained in the config.xml.

I'm using several self written script files - PHP, bash, perl, python, that I placed in the /root/ folder - and should be put there manually when I need to rebuild the system.
Rebuilding my pfSense is something I do onces in a decade, or so. So I installed the Notes package (a must have) where I put the files, with comments, etc, so I will fin things when needed, in 2030 or so.

I use also

[JeGr]

@gertjan said in Shellcmd that doesn't block (non-blocking) and allows boot to continue:

Rebuilding my pfSense is something I do onces in a decade, or so. So I installed the Notes package (a must have) where I put the files, with comments, etc, so I will fin things when needed, in 2030 or so.

Why not install and use the "Filer" package? I mean that's what it's there for, isn't it? ;)
Also it saves everything in config.xml for later use and restores if after a new installation. So no need for manually backing up and writing every script down in the Notes section?

Also filer and shellcmd got pretty well hand-in-hand :)

Cheers
\jens

[luckman212]

@jegr Never used the backup or filer packages although I've always been vaguely aware of them. Somehow I thought they were unmaintained for years and broken on recent versions of pfSense but I guess that's wrong. I'll check it out (as soon as pkg is fixed )