System Monitoring

System performance monitoring and troubleshooting commands

System Resource Monitoring

System resource monitoring and performance analysis

# Show system load
uptime

# Show system information
uname -a

# Show CPU information
cat /proc/cpuinfo

# Show memory information
cat /proc/meminfo

# Show disk usage
df -h

# Show disk usage by directory
du -h /path

# Show largest directories
du -h | sort -hr | head -10

# Show inode usage
df -i

# Show filesystem type
df -T

# Show memory usage
free -h

# Show memory usage continuously
free -h -s 5

# Show CPU usage
top

# Show CPU usage with 1 second interval
top -d 1

# Show I/O statistics
iostat -x 1

# Show network statistics
netstat -i

# Show system load average
cat /proc/loadavg

# Show system uptime
cat /proc/uptime

Individual commands:

uptime

uname -a

cat /proc/cpuinfo

cat /proc/meminfo

df -h

du -h /path

du -h | sort -hr | head -10

df -i

df -T

free -h

free -h -s 5

top

top -d 1

iostat -x 1

netstat -i

cat /proc/loadavg

cat /proc/uptime

Log Management

System log viewing and management with journalctl

# Show system logs
journalctl

# Show logs with follow
journalctl -f

# Show logs since boot
journalctl -b

# Show logs for specific service
journalctl -u service_name

# Show logs with priority
journalctl -p err

# Show logs with time range
journalctl --since "2024-01-01" --until "2024-01-02"

# Show kernel logs
journalctl -k

# Show boot logs
journalctl -b

# Show logs with specific unit
journalctl -u nginx.service

# Show logs with reverse order
journalctl -r

# Show logs with no pager
journalctl --no-pager

# Show logs with JSON output
journalctl -o json

# Show logs with verbose output
journalctl -o verbose

# Clear journal logs
sudo journalctl --vacuum-time=7d

# Show log disk usage
journalctl --disk-usage

Individual commands:

journalctl

journalctl -f

journalctl -b

journalctl -u service_name

journalctl -p err

journalctl --since "2024-01-01" --until "2024-01-02"

journalctl -k

journalctl -b

journalctl -u nginx.service

journalctl -r

journalctl --no-pager

journalctl -o json

journalctl -o verbose

sudo journalctl --vacuum-time=7d

journalctl --disk-usage

System Troubleshooting

System troubleshooting and diagnostic commands

# Check system errors
dmesg | grep -i error

# Check system warnings
dmesg | grep -i warning

# Show kernel messages
dmesg

# Show recent kernel messages
dmesg | tail -20

# Check hardware errors
dmesg | grep -i "hardware error"

# Check memory errors
dmesg | grep -i "memory error"

# Check disk errors
dmesg | grep -i "disk error"

# Check network errors
dmesg | grep -i "network"

# Show system call trace
strace -p 1234

# Show system call trace for command
strace command_name

# Show network connections
ss -tulpn

# Show network statistics
cat /proc/net/dev

# Check system limits
ulimit -a

# Check file descriptor limits
lsof | wc -l

# Check system load
cat /proc/loadavg

# Check system temperature (if available)
sensors

# Check system power status
cat /sys/class/power_supply/BAT0/status

Individual commands:

dmesg | grep -i error

dmesg | grep -i warning

dmesg

dmesg | tail -20

dmesg | grep -i "hardware error"

dmesg | grep -i "memory error"

dmesg | grep -i "disk error"

dmesg | grep -i "network"

strace -p 1234

strace command_name

ss -tulpn

cat /proc/net/dev

ulimit -a

lsof | wc -l

cat /proc/loadavg

sensors

cat /sys/class/power_supply/BAT0/status