Archives for March 2018

The iostat command is used for monitoring system input/output device loading by observing the time that the physical disks are active in relation to their average transfer rates. This information can be used to change system configuration to better balance the input/output load between physical disks and adapters. Below is a sample output when you […]

Domain Name System (DNS) is a network service that maps, or resolves, domain names to their respective IP addresses. It reduces the need for users to remember IP addresses because they can refer to machines on the network by name. The mapping done by /etc/hosts on a small local area network (LAN) is handled by […]

What is a PATH variable The PATH environment variable stores a colon separated list of locations to look for a command/application when one is run at the command line. For example, when running a command such as ls or vi the system checks all of the directories listed in the PATH (in order from left […]

Here is a short note/cheat sheet for Linux directory and file permissions. The table below gives numbers for all permission types of a File/Directory. Number          Permission Type             Symbol   0              No Permission                — […]

The skel directory Directory /etc/skel/ (skel is derived from the “skeleton”) is used to initiate home directory when a user is first created. A sample layout of “skeleton” user files is as shown below: # ls -lart /etc/skel total 32 drwxr-xr-x 4 root root 4096 Feb 4 2016 .mozilla -rw-r–r– 1 root root 124 Feb […]

It is important to find the process or application hogging memory of the system in case of a performance issue. The post lists few of the basic commands to calculate memory usage on a general Linux system. 1. Calculate memory usage using SAR # sar -r 1 10 Linux 2.6.32-504.el6.x86_64 (geeklab) 03/05/2018 _x86_64_ (16 CPU) […]

The file content of an RPM is usually installed. This means that the RPM files are copied onto their proper locations in the file system so that they may be used. For example, installing the bash binary RPM places the “/bin/bash” file into its expected location. To install an RPM, use either the “-i” or […]