Question: How to Delete Duplicate Rules in Routing Policy Database? Use the IP Rule selector for deleting the specific IP Rule. The syntax for the command is as follows: # ip rule del pref [selector] 1. First, list the routing policy database: # ip rule list 0: from all lookup local 32760: from all to […]
Archives for June 2019
Rman Backups Failing with RMAN-20004
The Problem Recovery catalog has been configured. Production Database has been cloned and a connection has been made from the clone to Catalog database using rman. DBID of the clone instance has not been changed, (so is identical with source DBID). Rman backup fails with: RMAN-00571: RMAN-00569: RMAN-00571: RMAN-03002: failure of resync command at 01/5/2009 […]
How to Install and Configure Kerberos in CentOS/RHEL 7
Confguration of Kerberos V5 1. Install krb5-libs, krb5-server, and krb5-workstation packages 2. Edit the /etc/krb5.conf and /var/kerberos/krb5kdc/kdc.conf to reflect your realm name and domain to realm mappings. A simple realm can be constructed by replacing instances of EXAMPLE.COM and example.com with your domain name (making sure you keep the same case), and by changing kerberos.example.com […]
–force V/s –nodeps : rpm command options to install or uninstall a package
These rpm options can potentially corrupt a Linux server so severely a reinstall may become necessary. So be cautious while playing with them. –force V/s –nodeps –force Ignore package and file conflicts for install — package might stop working properly leading to serious issues –nodeps Do not check dependencies — package might not work properly […]
Linux “rm” Command Examples
Unix includes two commands that you can use to delete files and directories: rm (remove) and rmdir (remove directory). You can also use “rm” command to remove a directory as well. In this post, we are going to discuss on rm command in Linux. rm is a Linux terminal command used to delete/remove files & […]
Oracle Database 12c2 : CPU_COUNT is Wrong
The Problem On Oracle database 12.2.0.1 version, cpu_count is not correct: OS has 128 CPU in total, however CPU_COUNT is only 104. SQL> show parameter cpu NAME TYPE VALUE ———————————— ———– —————————— cpu_count integer 104
How to configure resource groups for MySQL Server running on Linux
The following provides the procedure for configuring and using resource groups under Linux: 1. To use cgroups, you must install the “libcgroup” package on your system: # yum install libcgroup 2. Create a config file for cgroups: # vi /etc/cgconfig.conf mount { cpu = /cgroup/cpumem; cpuset = /cgroup/cpumem; memory = /cgroup/cpumem; } # High priority […]
How to Create and Query a BTRFS File System
The Basics The btrfs file system is designed to meet the expanding scalability requirements of large storage subsystems. As the btrfs file system uses B-trees in its implementation, its name derives from the name of those data structures, although it is not a true acronym. A B-tree is a tree-like data structure that enables file […]
How to configure CentOS/RHEL 6 system to not used last 3 passwords used
Question: How to change the password policy on a system so that a user cannot choose any of the last 3 passwords previously used? 1. Make sure that the file /etc/security/opasswd has the default permission (600). # ls -l /etc/security/opasswd -rw——- 1 root root 116 Sep 8 14:52 /etc/security/opasswd 2. Ensure you backup the file […]
How to Customize Linux Password Expiration and Complexity Requirements
1. Password Expiration To set the default password expiration when creating new accounts on CentOS/RHEL, edit the /etc/login.defs file. PASS_MAX_DAYS 100 Which means the maximum number of days a password may be used. Please check man page of login.defs for more options that can be set in /etc/login.defs.: $ man login.defs 2. Password Complexity The […]