Overview
The watch command refreshes and displays the output of a specific command periodically in the terminal. By default, it updates every 2 seconds and offers various options such as setting the interval and highlighting changes.
Key Features
- Real-time monitoring
- Periodic automatic updates
- Highlighting changes
- Full-screen display of command output
Key Options
Execution Control and Display
Generated command:
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Description:
`watch` Executes the command.
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Usage Examples
Basic Usage (Every 2 Seconds)
watch 'ls -l'Refreshes and displays the file list in the current directory every 2 seconds.
Monitor Disk Usage Every 5 Seconds
watch -n 5 'df -h'Checks disk usage (df -h) by updating every 5 seconds.
Monitor Log File with Highlighted Changes
watch -d 'tail -n 10 /var/log/syslog'Monitors the last 10 lines of a log file, highlighting new content as it's added.
Real-time CPU Usage Monitoring (No Title)
watch -t 'cat /proc/loadavg'Checks the system's load average (loadavg) in real-time without the title.
Monitor Network Connection Status
watch -n 1 'netstat -tulnp'Monitors currently open network ports and connection status every 1 second.
Tips & Precautions
The watch command is very useful for understanding system status in real-time.
Useful Combinations
Commonly used watch command combinations.
- watch -d 'ls -l' (Real-time file change monitoring)
- watch -n 1 'ps aux | grep [c]ommand' (Monitor specific process status)
- watch -d 'ip a' (Detect network interface status changes)
- watch -n 1 'free -h' (Real-time memory usage monitoring)
Precautions
Since watch repeatedly executes commands, be careful not to use commands that consume excessive system resources. In particular, commands with heavy network requests or disk I/O can cause system load.