How to Check System Error Log Patterns

How to Check System Error Log Patterns

Need to check system error log patterns on your Linux server? Want to monitor error logs, detect error patterns, and identify recurring errors? This guide shows you how to check error log patterns using built-in commands and automated monitoring with Zuzia.app.

For comprehensive log monitoring strategies, see Log Files Centralized Analysis Guide. For troubleshooting log issues, see Log Files Consuming Disk Space.

Why Checking Error Log Patterns Matters

System error logs indicate system problems and issues. When error patterns emerge, system problems can escalate, services can fail, and system reliability can be compromised. Checking error log patterns helps you detect recurring errors, identify system issues, track error trends, and maintain system reliability.

Method 1: View Error Logs

View error logs to see system errors:

Check System Logs

# View system log errors
sudo journalctl -p err

# View recent errors
sudo journalctl -p err -n 50

# View errors since boot
sudo journalctl -b -p err

# View errors by service
sudo journalctl -u service-name -p err

Check Application Logs

# View application errors
grep -i "error\|exception\|fail" /var/log/application.log | tail -20

# View error log files
tail -100 /var/log/syslog | grep -i "error\|fail"

# Check for critical errors
grep -i "critical\|fatal\|panic" /var/log/syslog | tail -20

# View error patterns
grep -i "error" /var/log/syslog | awk '{print $5, $6}' | sort | uniq -c

Method 2: Detect Error Patterns

Detect error patterns to identify recurring issues:

Identify Recurring Errors

# Count error occurrences
grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c | sort -rn

# View error patterns by time
grep -i "error" /var/log/syslog | awk '{print $1, $2, $3}' | sort | uniq -c

# Identify most common errors
grep -i "error" /var/log/syslog | awk -F: '{print $NF}' | sort | uniq -c | sort -rn | head -10

# View error frequency
grep -i "error" /var/log/syslog | awk '{print $1, $2}' | sort | uniq -c

Analyze Error Trends

# Track error trends over time
grep -i "error" /var/log/syslog | awk '{print $1, $2, $3}' | sort | uniq -c

# View error patterns by hour
grep -i "error" /var/log/syslog | awk '{print $3}' | cut -d: -f1 | sort | uniq -c

# Analyze error patterns by service
grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c | sort -rn

Method 3: Monitor Error Frequency

Monitor error frequency to track error trends:

Track Error Counts

# Count total errors
grep -i "error" /var/log/syslog | wc -l

# Count errors by type
grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c

# Count errors in last hour
grep -i "error" /var/log/syslog | grep "$(date +%b\ %d\ %H)" | wc -l

# Track error rate
grep -i "error" /var/log/syslog | awk '{print $1, $2}' | sort | uniq -c

Detect Error Spikes

# Check for error spikes
error_count=$(grep -i "error" /var/log/syslog | grep "$(date +%b\ %d\ %H)" | wc -l)
if [ $error_count -gt 100 ]; then
  echo "Error spike detected: $error_count errors in last hour"
fi

# View error spike patterns
grep -i "error" /var/log/syslog | awk '{print $1, $2, $3}' | sort | uniq -c | awk '$1 > 10'

Method 4: Automated Error Log Pattern Monitoring with Zuzia.app

While manual error log checks work for troubleshooting, production Linux servers require automated error log pattern monitoring that continuously tracks error logs, detects error patterns, and alerts you when error patterns indicate problems.

How Zuzia.app Error Log Pattern Monitoring Works

Zuzia.app automatically monitors error log patterns through scheduled command execution and log analysis. The platform checks error logs, detects error patterns, tracks error trends, and sends alerts when error patterns indicate problems.

Setting Up Error Log Pattern Monitoring

1. Add Scheduled Task for Error Monitoring

   • Command: grep -i "error\|exception\|fail" /var/log/syslog | tail -20
   • Frequency: Every 10 minutes
   • Alert when: Error patterns detected

2. Configure Error Pattern Detection

   • Command: grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c | awk '$1 > 10'
   • Frequency: Every 15 minutes
   • Alert when: Recurring errors detected

3. Set Up Error Frequency Monitoring

   • Command: grep -i "error" /var/log/syslog | grep "$(date +%b\ %d\ %H)" | wc -l
   • Frequency: Every 30 minutes
   • Alert when: Error frequency exceeds threshold

Custom Error Log Monitoring Commands

Add these commands as scheduled tasks:

# Check for errors
grep -i "error\|exception\|fail" /var/log/syslog | tail -20

# Detect error patterns
grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c | sort -rn

# Monitor error frequency
grep -i "error" /var/log/syslog | grep "$(date +%b\ %d\ %H)" | wc -l

# View error trends
grep -i "error" /var/log/syslog | awk '{print $1, $2}' | sort | uniq -c

Best Practices

1. Monitor Error Logs Continuously

Use Zuzia.app for continuous error log monitoring. Set up alerts before error issues become critical. Review error logs regularly.

2. Detect Error Patterns

Identify recurring errors. Track error trends. Analyze error patterns. Respond to error patterns proactively.

3. Track Error Trends

Monitor error frequency over time. Track error patterns. Identify error spikes. Plan error resolution.

Troubleshooting

Recurring Errors Detected

When recurring errors are detected:

1. Review error patterns: grep -i "error" /var/log/syslog | awk '{print $5}' | sort | uniq -c
2. Identify error sources
3. Fix root causes
4. Verify errors resolved

Error Spikes Detected

When error spikes are detected:

1. Check error frequency: grep -i "error" /var/log/syslog | grep "$(date +%b\ %d\ %H)" | wc -l
2. Review error patterns: grep -i "error" /var/log/syslog | tail -50
3. Investigate root causes
4. Fix issues causing error spikes

FAQ

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