Today,in this post we will learn, How to show line numbers with less command in Linux.In our previous post we have described about how to show line number with cat command. Less command is similar to more command but it has more features.As the name suggest, it read less output rather than reading the entire…
In this tutorial we will know, how to test rpm package before installation .You may have seen while installing the rpm package file by using rpm -i command, some problem may occur. It can be issue with dependency,GPG signature or corrupt rpm package etc. As a Linux System Engineer,this command is very useful and should…
In this post,we will know the linux command to find installation date and time of rpm package. As a Linux System Administrator,we take part in IT auditing activity. Sometimes for cross check we require the exact date and time of rpm file installed in Red Hat based Operating System (RHEL/CentOS/Scientific Linux). Hence,for auditing purpose,it is…
In this tutorial we will learn,how to allow only members of Wheel group to use su command.Means only members of wheel group can switch to another user by using su command.As we know that in Red Hat based operating system, wheel group is a special administrative group. To allow only Wheel group’s member to use…
In this post we will know,how to create a system account below uid 500 on Red Hat based operating system.In Red Hat based operating system,the system account are below UID 500. The UID below 500 are reserved for system use ,it should not be assigned to other users. We can easily check the system user…
In this tutorial we will learn, how to extract RPM package on Linux system. Extracting the rpm has one the important command and it will surely help you in System Administration. Many times I solved some problem which is caused by file corruption of particular package. Here is the story from my experience.One day,my colleague…
In this tutorial we will learn,how to free pagecache, dentries and inodes from memory on linux systems. The linux system is quite capable to manage the memory itself.Sometimes we require to flush the cache from memory in linux system . On writing the file /proc/sys/vm/drop_caches cause the kernel to drop clean caches, dentries and inodes…
In this post we will learn, how to create new directory in Linux system.Directory also called as folder(In Windows System). To create a new directory in Linux system we will use the command called mkdir. By using some options with mkdir command, we can do many things. To create a directory in Linux Use the…
While configuring the rsyslog, without verifying we hit the semanage command. And result was with error – bash: semanage: command not found . The method is applicable to Red Hat based operating system like RHEL 6 and CentOS 6.
In this tutorial,we will learn how to use yum command to download rpm file without installing in linux system.It was before RHEL 5 arrival, when I used to download the source rpm packages by using up2date -d package-name Now things are changed,in Red Hat based Operating System above version 5.x . We use the yum…
Question : I am newbie in Linux.I have a question,How to read logs which are writing continuously.I am using the Linux CentOS Server and wants to read the mail.log which is filling continuously.I just want to read the logs at the same time,when log file writing is running Answer: To read the file which are…
In this post we will learn about how to save iptables permanently on Ubuntu.When we work on Red hat based Operating system like RHEL and CentOS.We can permanently set the iptables rule in /etc/sysconfig/iptables file . When you work on Ubuntu Operating System,you may find you are only able to set the iptables rule temporarily….
In this article we will learn how to temporarily change the shell after login in Linux. The user can change its shell without doing logoff and restart the machine.For example a user require to change the shell in system to perform various commands.
In this post,I am sharing a useful option with linux grep command.In this tutorial, we will use grep command to show lines after and before the keyword . As a Linux System Engineer, sometimes I get the requirement to print lines above and below of a particular keyword in the file. Generally if you only…
In this post I am sharing a small and useful tip about, how to know last command run successfully in Linux and Unix .The post will explain ,to get the exit status of command used last time. As a System Engineer, sometimes I have to check the success status of last command I run on…