Archives for September 2021

One of the earliest parts of network troubleshooting is sending test packets between two systems. This is done using a TCP/IP utility called ping. The ping command will generate a response request from the sending computer and should receive a reply from the destination computer. Possible outcomes of the ping command include: Reply from [host]: […]

The ifconfig command enables a user to view the current IP addressing information for each NIC recognized by the system. Viewing the IP address configuration is one of the earliest steps in network troubleshooting. The ifconfig command shows the IP address, subnet mask, broadcast ID, MAC address, basic performance information, and NIC name. The tool […]

The dmidecode command dumps the system’s Desktop Management Interface (DMI) table and presents it in a human-readable format. The DMI table is an industry-standard for tracking information about hardware components. It separates components into types, with each type given a number—for example, type 4 is a processor, type 39 is a power supply, etc. Like […]

The lspci command is used to display information about devices that are connected to the system’s PCI buses. By default, the output will list the logical slot address (typically in the format Bus:Device.Function), the device’s class (such as network controller, storage controller, input device, or bridge device), the vendor name, and the device name. Like […]

The lsusb command is used to display information about devices that are connected to the system’s USB buses. This command scans the /dev/bus/usb/ directory for information. By default, the command will print the number of the bus and the connected device, the ID of the device, and the name of the vendor and product matching […]

The swapon command is used to activate a swap partition in a specified device. The swapoff command is used to deactivate the swap space on a device. Some of the frequently used swapon and swapoff command options are given in the following table. Option Used To swapon -e Skip non-existent devices. swapon -a Activate all […]

The mkswap command is used to create swap space on a storage partition. It is typically used when you wish to move swap space to a different partition than the one that was created during system installation. For example, you might want to save space on a low-capacity boot drive. It provides options to perform […]

The free command parses the /proc/meminfo file for easier analysis of memory usage statistics. Its default behavior is to display the following information about system memory and swap space: The total memory. The total used. The total free. The total shared. The total buffered and cached. The total available for starting new apps (estimated). Syntax […]

The sar command displays system usage reports based on data collected from system activity. These reports consist of various sections, each of which consists of the type of data and the time at which the data was collected. The default mode of the sar command displays CPU usage in various time increments for each category […]

Different commands are used to send signals to processes to terminate or “kill” them. This is necessary when a process becomes unresponsive (hangs), causes system instability, or fails to relinquish control over a file you’re trying to modify. Using the pid number to terminate processes You can use the kill command with the process table […]