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How do I use the vmstat command?

For a more concise understanding of system performance, try vmstat. With vmstat, it is possible to get an overview of process, memory, swap, I/O, system, and CPU activity in one line of numbers: procs memory swap io system cpu r b swpd free buff cache si so bi bo in

How do I use the top command?

While free displays only memory-related information, the top command does a little bit of everything. CPU utilization, process statistics, memory utilization — top monitors it all. In addition, unlike the free command, top’s default behavior is to run continuously; there is no need to use the watch command. The display

How do I use the free command?

The free command displays system memory utilization. Here is an example of its output: total used free shared buffers cachedMem: 255508 240268 15240 0 7592 86188-/+ buffers/cache: 146488 109020Swap: 530136 26268 503868 The Mem: row displays physical memory utilization, while the Swap: row displays the utilization of the system swap

Is Your RAM Not Being Recognized?

Sometimes, the kernel does not recognize all of your memory (RAM). You can check this with the cat /proc/meminfo command. Verify that the displayed quantity is the same as the known amount of RAM in your system. If they are not equal, add the following line to the /boot/grub/grub.conf: Mem=xxM

Is Your System Displaying Signal 11 Errors?

A signal 11 error, commonly know as a segmentation fault, means that the program accessed a memory location that was not assigned. If you receive a fatal signal 11 error during your installation, it is probably due to a hardware error in memory on your system’s bus. A hardware error

What is the recommended partitioning scheme?

A swap partition (at least 256 MB) — swap partitions are used to support virtual memory. In other words, data is written to a swap partition when there is not enough RAM to store the data your system is processing. If you are unsure about what size swap partition to

How do I add rules to the iptables firewall?

Some examples are given below: To allow access to port 80 on the firewall, append the following rule: iptables -A INPUT -p tcp -m tcp –sport 80 -j ACCEPT iptables -A OUTPUT -p tcp -m tcp –dport 80 -j ACCEPT This allows regular Web browsing from websites that communicate via

What is the /proc file system?

The /proc directory — also called the proc file system — contains a hierarchy of special files which represent the current state of the kernel — allowing applications and users to peer into the kernel’s view of the system. Within the /proc directory, one can find a wealth of information

Get detailed hardware information through CentOS

The /etc/sysconfig/hwconf file lists all the hardware that kudzu detected on the system, as well as the drivers used, vendor ID, and device ID information. The kudzu program detects and configures new and/or changed hardware on a system. The /etc/sysconfig/hwconf file is not meant to be manually edited. If edited,

What are primary network configuration files?

The primary network configuration files are as follows: /etc/hosts — The main purpose of this file is to resolve hostnames that cannot be resolved in any other way. This file should contain a line specifying the IP address of the loopback device ( as localhost.localdomain. /etc/resolv.conf — This file specifies

Why Use OpenSSH?

If you use OpenSSH tools, you are enhancing the security of your machine. All communications using OpenSSH tools, including passwords, are encrypted. Telnet and ftp use plain text passwords and send all information unencrypted. The information can be intercepted, the passwords can be retrieved, and your system could be compromised