This article discusses the issue where syslog messages are not being logged on Juniper devices in /var/log folder, even after resolving file system-related problems. 

Messages file would not be seen in /var/log.

{master}
user@device> show log m?
Possible completions:
mgd-api              Size: 0, Last changed: Aug 09 2022

<<<<<No messages file found 

The primary cause of this issue could be a full file system, which prevents logging. Even after addressing the file system fullness, syslog messages might still fail to log.

To resolve the issue, reconfiguring the syslog configuration is necessary.

>configure

#delete system syslog file messages any notice

#commit

#set system syslog file messages any notice

#commit