The Problem After a server has been restarted after patching – The error below can possibly be witnessed during boot and the same error is visible in /var/log/boot.log: Starting udev: udevd inotify_init failed: too many open files Due to udev fails to start, network and bonding interfaces are missing (including modules/drivers). The Solution There was […]
Archives for December 2018
Filesystems Are Not Getting Mounted in Order on CentOS/RHEL 7
The Problem On CentOS/RHEL 7, Any filesystem volumes are not getting mounted in order as per the /etc/fstab entries. The Solution Unlike CentOS/RHEL 6 and earlier versions, on CentOS/RHEL 7 the boot process is faster. Because of the parallel nature of process startup, specific target units startup orders are not deterministic. All the Filesystems are […]
How to control resource (cgroup) with systemd for user process group in CentOS/RHEL 7
The Basics RHEL7 moves the resource management settings from the process level to the application level by binding the system of cgroup hierarchies with the systemd unit tree. The old way of configuring cgroup, by means of editing several /etc/cg*.conf files is still available but no longer recommended. Systemd provides three unit types(slice, scope, service) […]
How to run rsyslog as a non-root user in CentOS/RHEL 7
You can utilize the $PrivDropToUser, $PrivDropToUserID, $PrivDropToGroup, and $PrivDropToGroupID configuration directives to run rsyslog as a non-root user. When these variables are used, rsyslog will start as root, but will drop to the specified user and/or group after initialization. The daemon will then run in accordance with the permissions of the specified user or group. […]
Starting iptables Fails with Error “Another app is currently holding the xtables lock”
The Problem Updating the package iptables to iptables-1.4.7-16.0.3.el6, the service fails to start after a stop. # service iptables stop iptables: Setting chains to policy ACCEPT: filter [ OK ] iptables: Flushing firewall rules: [ OK ] iptables: Unloading modules: [ OK ] # service iptables start iptables: Applying firewall rules: Another app is currently […]
Using cut on Linux Terminal
The cut command The cut command is most often used to select single columns of data from input separated by a single character, such as an /etc/passwd file. For example, the cut command is used to extract specified columns/characters of a piece of text, which is given as follows: -c: Specifies the filtering of characters […]
Supported and Recommended File Systems on Linux
Purpose of this post is to give systems administrators an overview and a comparison of File Systems available on Linux. Linux File Systems One of the most interesting features of the Linux OS is its variety of file systems. File systems can be defined and built on a partition basis. VFAT, ext2, ext3, ext4 and […]
What are the mount options to improve ext4 filesystem performance in Linux
The default mount options are deployed usually for maximum performance while maintaining safety for general usage. There are some mount options to optimize ext4 file system according to the needs of the target usage. barrier=0 This disables the write barriers in Journaling Block Device(JBD). Ext4 file system has barrier=1 by default where ext3 has barrier=0. […]
OpenShift Container Platform : User creation and deletion using htpasswd command
htpasswd is one of the identity providers in openshift. In order to access OCP cluster have to create users, the users can create using htpasswd command, it has many options can use appropriately. -c Create a new file. -n Don’t update file; display results on stdout. -b Use the password from the command line rather […]
How to gzip all or specific files in Linux
The gzip (GNU zip) utility is older and less efficient than bzip2. Its flags and operation are very similar to those of bzip2. A file compressed by gzip is marked with a .gz filename extension. Linux stores manual pages in gzip format to save disk space; likewise, files you download from the Internet are frequently […]