Trying to modify a Zabbix Template trigger expression

[ChristianHo]

Hello,

I did now try for hours to modify a Zabbix trigger expression and could not solve it. Maybe someone got a hint to the right direction for me.

Original trigger:

{Template OS Linux:vfs.fs.size[{#FSNAME},free].last(0)}<5000000000

Modified trigger (cannot save it, since it is considered invalid):

{Template OS Linux:vfs.fs.size[{#FSNAME},free].last(0)}<5000000000 
or 
({Template OS Linux:{#FSNAME}.regexp(/boot)=0}
and
{Template OS Linux:vfs.fs.size[{#FSNAME},free].last()}<50000000)

What I try is to check for a different value, if the FSNAME (Filesystem Name) is /boot. I tried multiple variants but never got the fsname expression to work.

Am I approaching this the wrong way ?

Best regards

Christian