Basic System Monitoring Commands

I am going to discuss some basic system monitoring commands here. Nothing big, most of the systems will have it pre-installed.

• top: Displays pid, user, CPU, physical memory and swap usage in real time. You can press M - to sort by memory, S - to sort by time, P - to sort by CPU interactively. You can also press u and k to check out user processes and kill one respectively.
  
• ps: It shows a list of processes. Use option -A for the entire list, -ef to get a detailed view and -u for user processes.
  
• vmstat: It provides statistics for processors, memory, swap, I/O and CPU.
  
• df: This is used to get information about the file system. It'll show you the size, used space, available space, used %, and mount information.
  
• du: It is used to check out the size of files. It goes recursively if you do not specify the file name.
  
• iostat: It provides the information about the Kernel version, average cpu usage and hardware devices. You might need to install sysstat package for this.
  
• who and w: Provides information regarding the number of people logged in. w provides more detailed report.