A high number here would indicate that the I/O is slow, or is being held up in some other process. The %iowait column tells us if the CPU is wasting a lot of time waiting for I/O operations to complete. 12: iostat outputĪs you can see, the first section of the output is the average CPU usage divided into sections, including userspace, system space, CPU steal, CPU idle, and I/O wait. Figure 12 shows the output of iostat on an Ubuntu 18.04 computer. Using iostat, we can decide if we need to modify system configuration to allow for better or balanced I/O operations. It also provides the CPU utilization for such operations. Iostat is used to monitor such I/O activity on all disks and partitions on a computer. And much like other resources, there's a limit to this bandwidth. In other words, every process performs a number of I/O (input/output) operations every second. Whenever a process runs, along with CPU and memory, the process also consumes disk bandwidth. These files are written to the disks attached to the computer. 7: lsof with user filterĪs we’ve already mentioned, everything in a Linux computer is controlled using files. Command to filter files of processes listening to a certain port: lsof -i TCP:22įigure 7 shows the list of files opened and owned by the user root.Command to filter files by owner: lsof -u root. We can use various options with the command to filter files for a particular user, or by files used by a certain port, and so on. This table gives us a lot of information, including the command used to run the process that owns the file, the PID, the user who owns the process, the type and size of the file, and more. lsof (or list of open files) is a handy command to quickly see the list of open files and associated processes.įigure 6 shows a truncated list of the lsof command output. So, any issues with hardware, or even software on a Linux machine has to be debugged using files. For example, the network adapters-and even any USB accessory that we plug in-are all controlled using files.
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