The online Reference Manual (man) pages provide detailed descriptions and usage of the commands. You can use the man command to display the man page entry that explains a given command. The syntax of the man command is as follows. $ man command $ man option command $ man option filename Displaying the Man Pages […]
Archives for December 2017
CentOS / RHEL : How to install Open Virtual Machine Tools for Virtual machines Hosted on VMWare
Open VM Tools (OVT) consists of a suite of virtualization utilities that improves the functionality, administration, and management of virtual machines on VMWare hypervisors. This simplifies the deployment of virtual machines on VMware hypervisors. OVT is a set of services and modules that enable several features in VMware products for better management of guests. This […]
How to add swap file in Solaris
Swap space is used as virtual memory storage areas when the system does not have enough physical memory to handle current processes. You might have to add swap space to your system if it does not have enough swap space or if recommended by your software application vendor. Follow the steps below to add swap […]
How to Schedule Jobs with ‘at’ command under Linux
If you want to schedule a job to run one time only in the future (instead of scheduling it on a regular basis with cron) you can use the at command. To use at, you must first verify that the at package has been installed and that the atd service has been started. You define […]
Defining System Jobs Using Cron under Linux
The cron daemon can be configured to run scheduled system jobs. For system jobs, the user with whose permissions the command is run must also be specified. Enter the username between the time definition (the first five fields) and the command (which now becomes the seventh field). You define system jobs in the /etc/crontab file […]
How to schedule Jobs with Cron in Linux
You will find that there are many tasks that need to be carried out on a regular basis on your Linux system. For example, you may need to update a database or back up users’ data in the /home/ directory. While you could run these tasks manually, it would be more efficient (and more reliable) […]
Linux OS Service ‘syslog’
Syslog is the general standard for logging system and program messages in the Linux environment. This service constitutes the system log daemon, where any program can do its logging (debug, security, normal operation) through in addition the Linux kernel messages. In principle, the logs handled by syslog are available in the /var/log/ directory on Linux […]
CentOS / RHEL 5 : How to use the faillog command to track failed login attempts
The failog command formats and displays the contents of the failure log (/var/log/faillog) and maintains failure counts and limits. The faillog functionality has to be enabled by adding the pam_tally.so module to the respective file in /etc/pam.d/. Below are the steps to setup the faillog utility to track failed login attempts. 1. Edit the /etc/pam.d/system-auth […]
Comparing NET-TOOLS V/s IPROUTE Package Commands (ip Vs ifconfig command comparison)
Below is a short comparison of the commands provided by the net-tools V/s iproute package. Basically we will be comparing the commands ifconfig V/s ip. NET-TOOLS COMMANDS IPROUTE COMMANDS arp -a ip neigh arp -v ip -s neigh arp -s 192.168.1.1 1:2:3:4:5:6 ip neigh add 192.168.1.1 lladdr 1:2:3:4:5:6 dev eth1 arp -i eth1 -d 192.168.1.1 […]
5 Useful Command Examples to Monitor User Activity under Linux
One of the most critical tasks you have as a system administrator is to monitor your system for any suspicious activity that might indicate a security compromise and act on it. You should evaluate login activity for signs of a security breach, such as multiple failed logins. NOTE: Reviewing files such as /var/log/messages can also […]