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Troubleshooting Log Files

The only real unique entity for logging on Cumulus Linux compared to any other Linux distribution is switchd.log, which logs the HAL (hardware abstraction layer) from hardware like the Broadcom or Mellanox Spectrum ASIC.

Read this guide on NixCraft to understand how /var/log works.

Log File Descriptions

/var/log/alternatives.logInformation from update-alternatives.
/var/log/aptInformation from the apt utility. For example, from apt-get install and apt-get remove.
/var/log/audit/*Information stored by the Linux audit daemon, auditd.
/var/log/autoprovisionOutput generated by running the zero touch provisioning script (ZTP).
/var/log/boot.logInformation that is logged when the system boots.
/var/log/btmpInformation about failed login attempts. Use the last command to view the btmp file. For example:
cumulus@switch:~$ last -f /var/log/btmp | more
/var/log/clagd.logStatus of the clagd service.
/var/log/dpkg.logInformation logged when a package is installed or removed using the dpkg command.
/var/log/frr/*FRRouting - Used to troubleshoots routing, such as an MD5 or MTU mismatch with OSPF.
/var/log/gunicornError and access events in Gunicorn.
/var/log/installer/*Directory containing files related to the installation of Cumulus Linux.
/var/log/lastlogFormats and prints the contents of the last login log file.
/var/log/netd.logLog file for NCLU.
/var/log/netd-history.logLog file for NCLU configuration commits.
/var/log/nginxErrors and processed requests in NGINX.
/var/log/ntpstatsLogs for network configuration protocol.
/var/log/openvswitch/*ovsdb-server logs.
/var/log/ptmdPrescriptive Topology Manager (PTM) errors and information.
/var/log/switchd.logThe HAL log for Cumulus Linux.
This is specific to Cumulus Linux. Any switchd crashes are logged here.
/var/log/syslogThe main system log, which logs everything except auth-related messages.
The primary log; grep this file to see what problem occurred.
/var/log/wtmpLogin records file.