Expected:
Consistent behavior with zabbix agent.

Issue:
It is reported that negative lookahead in cmdline parameter of proc.num is not working after changing from zabbix agent(4.0.6) to zabbix agent2(6.0.19).

Here's the result I have tested.
zabbix_get is 6.0.25. And libpcre2(10.40) is installed on both two hosts.

• Zabbix agent(6.0.25)

  $ ps -ef |grep sshd
  root        1453       1  0 18:47 ?        00:00:00 sshd: username [priv]
  username      1472    1453  0 18:47 ?        00:00:00 sshd: username@pts/0
  root        1598       1  0 18:47 ?        00:00:00 sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups
  username     37866    1473  0 18:51 pts/0    00:00:00 grep --color=auto sshd
  $
  

  $ zabbix_get -s 192.168.64.15 -k proc.num[,,,"sshd:"]
  3
  $ zabbix_get -s 192.168.64.15 -k proc.num[,,,"sshd:(?! username)"]
  1
  $
  

  The correct values are acquired.

• Zabbix agent2(6.0.25)

  $ ps -aux |grep ssh
  root         743  0.0  0.2  16228  8192 ?        Ss   17:21   0:00 sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups
  root        1541  0.0  0.2  21980 10112 ?        Ss   17:21   0:00 sshd: username [priv]
  username      1543  0.0  0.1  21980  6192 ?        S    17:21   0:01 sshd: username@pts/0
  username      6690  0.0  0.0   4296  1792 pts/0    S+   18:06   0:00 grep --color=auto ssh
  $ 
  

  $ zabbix_get -s 192.168.64.14 -k proc.num[,,,"sshd:"]
  3
  $ zabbix_get -s 192.168.64.14 -k proc.num[,,,"sshd:(?! username)"]
  0
  $
  

  The value 0 is wrong. It should be 1.

Regards,