Note: This is an RHCSA 7 exam objective.

System Activities

To get an instantaneous image of a server activity (use ‘virt-top‘ on a KVM hypervisor), type:

# top

To get details about processes, type:

# ps -edf

Process Priority

To start a process (here script.sh) with a low priority, type:

# nice -n 10 ./script.sh

To change the priority (here +5) of an already running process, get its PID (Process ID) through top or ps (here 789) and type:

# renice +5 789

Alternatively:

# renice +5 `pgrep script.sh`

Process Deletion

To kill the process, get its PID through top or ps (here 789) and type:

# kill -9 789

Alternatively:

# pkill script.sh

System Reporting

To display details about IO activities, type:

# iostat

To show network card activities, type:

# netstat -i

To display socket activities, type:

# netstat -a

To get details about virtual memory activities (memory, swap, run queue, cpu usage, etc) every 5 second, type:

# vmstat 5

To get a full report of a server activity, type:

# sar -A

Additional Resources

You can also watch a video by Sander van Vugt about Understanding Linux Memory Usage (4min/2016).