RegExp unexpected results

[ryan_frank]

Implementing vfs.file.regexp checks to look for data inside a file (capture for inventory and validation). Following the instructions from the manual I created the entry per the guidelines: vfs.file.regexp[file,regexp,<encoding>,<start line>,<end line>,<output>]

$ /usr/sbin/zabbix_agentd -t "vfs.file.regexp[/etc/opt/app/ENV,"^VERSION",,,,]"
vfs.file.regexp[/etc/opt/app/ENV,^VERSION,,,,] [s|VERSION=7.1]

I get the whole output, awesome right! nope... then I add the output option to juts get the 7.1 it does not work...

$ /usr/sbin/zabbix_agentd -t "vfs.file.regexp[/etc/opt/app/ENV,"^VERSION",,,,\0]"
vfs.file.regexp[/etc/opt/app/ENV,^VERSION,,,,\0] [s|VERSION]

\0 zero works! shows me the item matched.

$ /usr/sbin/zabbix_agentd -t "vfs.file.regexp[/etc/opt/app/ENV,"^VERSION",,,,\1]"
vfs.file.regexp[/etc/opt/app/ENV,^VERSION,,,,\1] [s|]

Nothing for \1-\9...

If I make the regex any more complicated I am greeted with an "Invalid key format" even if just adding ranges of numbers/characters...

$ /usr/sbin/zabbix_agentd -t "vfs.file.regexp[/etc/opt/app/ENV,"VERSION=[0-9].[0-9]",,,,]"
vfs.file.regexp[/etc/opt/app/ENV,VERSION[0-9],,,,] [m|ZBX_NOTSUPPORTED] [Invalid item key format.]

Any ideas on what I am doing wrong? Why wont the output work and why does any expanded options in the regexp yield the invalid format, I have tested in regexp and it works outside of zabbix.

$ cat /etc/opt/app/ENV | grep '^VERSION=[0-9].[0-9]'
VERSION=7.1

[Hamardaban]

You didn't specify a group in the regular expression. So \1 doesn't output anything. \0 matches the entire expression.
vfs.file.regexp[/etc/opt/app/ENV,"(^VERSION=[0-9]\.[0-9])",,,,\1]

[ryan_frank]

You didn't specify a group in the regular expression. So \1 doesn't output anything. \0 matches the entire expression.
vfs.file.regexp[/etc/opt/app/ENV,"(^VERSION=[0-9]\.[0-9])",,,,\1]

Well I will be... THANK YOU! setting the group gave me what I needed! "^VERSION=([0-9]\.[0-9].*)",,,,\1 worked like a charm...

Thank you for helping clear up my stupidity... Still have a lot to learn about regexp...