Keywords When Browsing Linux Logs

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Troubleshooting Linux systems often requires browsing logs to identify issues effectively. Knowing the right keywords to search for can help narrow down problems quickly. This guide categorizes common issues and provides relevant keywords and log file suggestions for Linux systems, whether in cloud environments or on-premises.

1. Authentication and Access Issues

Keywords:

  • Failed password, authentication failure, pam_unix, sudo, sshd, login, access denied

Logs to Check:

  • /var/log/auth.log
  • /var/log/secure
  • /var/log/messages
  • /var/log/syslog

2. Network Issues

Keywords:

  • Network, eth, interface, timeout, unreachable, connection refused, connection reset, no route to host

Logs to Check:

  • /var/log/messages
  • /var/log/syslog
  • dmesg

3. Disk and File System Issues

Keywords:

  • I/O error, disk full, read-only file system, quota exceeded, no space left on device, mount, unmount, ext4, xfs

Logs to Check:

  • /var/log/messages
  • /var/log/syslog
  • /var/log/kern.log
  • dmesg

4. Process and Application Crashes

Keywords:

  • Segfault, core dumped, oom-killer, killed process, crash, panic, out of memory

Logs to Check:

  • /var/log/messages
  • /var/log/syslog
  • /var/log/kern.log
  • dmesg

5. Service and Daemon Failures

Keywords:

  • Failed to start, stopped, service unavailable, service failed, inactive, error starting, failed service

Logs to Check:

  • /var/log/syslog
  • /var/log/messages
  • /var/log/systemd
  • /var/log/journal
  • /var/log/service-name.log

6. Hardware and Kernel Issues

Keywords:

  • Kernel, hardware error, driver, irq, firmware, acpi, temperature, overheating

Logs to Check:

  • /var/log/kern.log
  • dmesg
  • /var/log/messages

7. Security and Firewall Issues

Keywords:

  • Firewall, iptables, denied, blocked, dropped packet, unauthorized access, security

Logs to Check:

  • /var/log/firewalld
  • /var/log/syslog
  • /var/log/messages

8. Boot and Shutdown Issues

Keywords:

  • Boot, shutdown, init, failed to mount, grub, timeout during boot, emergency mode

Logs to Check:

  • /var/log/boot.log
  • /var/log/syslog
  • /var/log/messages
  • dmesg

9. Software Installation and Update Issues

Keywords:

  • Yum, apt, zypper, failed dependency, package not found, installation failed, update error

Logs to Check:

  • /var/log/yum.log
  • /var/log/apt/history.log
  • /var/log/zypper.log
  • /var/log/messages

10. System Resource Issues

Keywords:

  • High CPU, load average, memory usage, disk I/O, swap usage, out of resources

Logs to Check:

  • /var/log/syslog
  • /var/log/messages
  • dmesg

Tips for Efficient Log Searching

Use tools like:

  • grep: To search specific keywords in logs.
  • journalctl: To view and filter systemd logs.
  • tail: To monitor logs in real-time.

These tools can help you quickly search for specific issues within Linux logs.

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