Jobs
A comprehensive guide to monitoring system resources, managing processes, and handling jobs in Linux.
📊 System Resource Monitoring
System Overview
# System information
uname -a # System and kernel information
hostnamectl # System and OS information
lsb_release -a # Distribution information
uptime # System uptime and load
# Resource usage overview
top # Interactive process viewer
htop # Enhanced interactive process viewer
glances # Advanced system monitorMemory Monitoring
# Memory usage
free -h # Memory usage in human-readable format
vmstat # Virtual memory statistics
cat /proc/meminfo # Detailed memory information
swapon --show # Show swap usage
smem # Memory usage per process
# Memory management
sync # Flush file system buffers
echo 3 > /proc/sys/vm/drop_caches # Clear cache
swapoff -a && swapon -a # Reset swapCPU Monitoring
# CPU information
lscpu # CPU architecture information
cat /proc/cpuinfo # Detailed CPU information
mpstat # CPU statistics
sar -u # CPU utilization report
stress-ng # CPU stress testing
# Load average
w # Show system load
uptime # Quick load average view
cat /proc/loadavg # Raw load average dataDisk Monitoring
# Disk usage
df -h # Disk space usage
du -sh /* # Directory sizes
iostat # I/O statistics
iotop # I/O monitoring per process
fio # I/O performance testing
# Disk health
smartctl -a /dev/sda # SMART disk information
hdparm -tT /dev/sda # Disk read speed test
badblocks -v /dev/sda # Check for bad sectors🔄 Process Management
Process Information
# Process listing
ps aux # List all processes
ps -ef # Full process listing
pstree # Process tree view
pidof process_name # Find process ID
# Process details
ps -p PID -f # Detailed process info
cat /proc/PID/status # Process status
strace -p PID # Trace process system calls
lsof -p PID # List open files by processProcess Control
# Process manipulation
kill PID # Terminate process
killall process_name # Kill by process name
pkill pattern # Kill by pattern
renice -n 10 -p PID # Change process priority
nice -n 10 command # Start with priority
# Process signals
kill -l # List all signals
kill -9 PID # Force kill (SIGKILL)
kill -15 PID # Graceful termination (SIGTERM)
kill -19 PID # Suspend process (SIGSTOP)👥 Job Control
Job Management
# Job control
jobs # List background jobs
bg %job_number # Send job to background
fg %job_number # Bring job to foreground
ctrl+z # Suspend current job
command & # Start job in background
# Job scheduling
at now + 1 hour # Schedule one-time job
batch # Run job when system load permits
atq # List pending jobs
atrm job_number # Remove scheduled jobCron Jobs
# Cron management
crontab -l # List cron jobs
crontab -e # Edit cron jobs
crontab -r # Remove all cron jobs
# Cron examples
# MIN HOUR DOM MON DOW CMD
0 * * * * command # Run hourly
0 0 * * * command # Run daily at midnight
0 0 * * 0 command # Run weekly📈 Performance Analysis
System Performance
# Performance tools
sysstat # System performance tools
sar # System activity reporter
perf # Performance analysis tools
strace # System call tracer
# Performance monitoring
vmstat 1 # Virtual memory stats every second
iostat -xz 1 # I/O stats every second
mpstat -P ALL 1 # CPU stats every secondNetwork Performance
# Network monitoring
netstat -tuln # Active connections
ss -tuln # Socket statistics
iftop # Network bandwidth monitor
nethogs # Per-process network traffic
# Network testing
iperf3 # Network bandwidth testing
mtr hostname # Network path analysis
tcpdump # Network packet analysis🔍 Log Monitoring
System Logs
# Log viewing
journalctl # View systemd logs
tail -f /var/log/syslog # Follow system log
grep -i error /var/log/* # Search errors in logs
dmesg # Kernel ring buffer
# Log analysis
logwatch # Log analysis and reporting
fail2ban-client status # Intrusion prevention status
last # Login history
who # Current logins🛠️ Advanced Monitoring
Resource Limits
# System limits
ulimit -a # Show all limits
/etc/security/limits.conf # Configure limits
sysctl -a # Kernel parameters
nice # Run with modified priorityContainer Monitoring
# Docker monitoring
docker stats # Container resource usage
docker top # Container processes
docker logs # Container logs
ctop # Container monitoring tool💡 Best Practices
Regular Monitoring
Set up automated monitoring
Define resource thresholds
Configure alerts
Keep monitoring history
Resource Management
Monitor resource trends
Plan capacity
Set resource limits
Optimize usage
Process Control
Use appropriate signals
Monitor critical processes
Set process priorities
Handle zombie processes
Job Scheduling
Document scheduled jobs
Monitor job completion
Handle job failures
Manage job priorities
🔧 Troubleshooting
Common Issues
# High CPU usage
top -c # Identify CPU-intensive processes
ps aux --sort=-%cpu # Sort by CPU usage
perf top # CPU performance analysis
# Memory issues
free -h # Check memory usage
ps aux --sort=-%mem # Sort by memory usage
dmesg | grep -i oom # Check OOM killerPerformance Issues
# System performance
sar -q # Load average analysis
sar -r # Memory utilization
sar -b # I/O statistics
sar -n DEV # Network statistics
# Process issues
strace -p PID # Debug process
ltrace -p PID # Library call tracer
lsof # List open files
fuser # Identify process using filesLast updated
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