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Unix Articles
Page 4 of 6
Difference between CSH and BASH
Linux is a popular operating system among computer enthusiasts. It is a free and open operating system. Shells are the screens that we utilize to control an operating system. Shells are CSH and BASH. Shells act as a channel for communication between programmers and the device. We issue orders and obtain results. The C-shell was named after the C programming syntax. One of its many benefits is the ability to regulate jobs. It may be accessed via script shell command runner and interactive shell login. It might not be easy to use at times. Bash is a shell software similar ...
Read MoreLimiting Process Resource Consumption in Unix
Introduction In a Unix-based operating system, it is important to manage the resources consumed by processes to ensure that the system runs smoothly. If a process consumes too many resources, it can cause the system to become slow or unresponsive. In some cases, it can even cause the system to crash. Therefore, it is important to be able to limit the resources that a process can consume. There are several ways to limit the resource consumption of processes in Unix. One way is to use the ulimit command, which allows you to set limits on the resources that a process ...
Read MoreDifference between IBM and SCO
The dispute between IBM and SCO began in March 2003, when SCO Group, a Utah-based firm, filed a lawsuit against IBM, claiming that IBM had broken the license agreement for AIX (IBM's in-house version of Unix) that it had signed with AT&T and that SCO now controlled. By offering AIX to other companies, SCO Group said IBM was in breach of contract. More than a billion dollars were sought in damages for the complaint, which also alleged illegal competition and a violation of the contract. Just two months after filing suit, SCO claimed to have found more UNIX code ...
Read MoreWorking with tmux session
Tmux is a terminal multiple for Unix OS. It provides multiple terminal sessions to its users. It is used when we are using cloud-based services (like Azure, AWS) for the creation of separate terminals for different remote users.While working with web services, one needs to create an EC2 instance on the webserver provided by the company to work on it by creating a session.Now, let’s see the steps of working on a UNIX (Ubuntu) webserver.Step 1 − Write/copy the IP address of your AWS console and download the key file from the console. You will get these from your vendor ...
Read MoreIs there any whoami function or command in MySQL like UNIX?
There is no whoami function in MySQL. The whoami can be used to know the current user in UNIX. Use user() or current_user() function from MySQL for the same purpose.The following is the output.+-----------+ | version() | +-----------+ | 8.0.12 | +-----------+ 1 row in set (0.00 sec)Case 1 −Using CURRENT_USER() function.The query to know the current user is as follows.mysql> select current_user();The following is the output.+----------------+ | current_user() | +----------------+ | root@% | +----------------+ 1 row in set (0.00 sec)Case 2 − Using USER() function.The query is as follows −mysql> select user();The following is ...
Read MoreProcess Synchronization in Linux
Process synchronization in Linux involves providing a time slice for each process so that they get the required time for execution.The process can be created using the fork() command in Linux. The creating process is called the parent process and the created process is the child process. A child process can have only one parent but a parent process may have many children. Both the parent and child processes have the same memory image, open files and environment strings. However, they have distinct address spaces.A diagram that demonstrates the fork() command is given as follows −Orphan ProcessesThere are some processes ...
Read MoreWhat are Shell Commands?
The shell is the command interpreter on the Linux systems. It the program that interacts with the users in the terminal emulation window. Shell commands are instructions that instruct the system to do some action.Some of the commonly used shell commands are −basenameThis command strips the directory and suffix from filenames. It prints the name of the file with all the leading directory components removed. It also removes a trailing suffix if it is specified.Example of basename is as follows −$ basename country/city.txtThis gets the name of the file i.e. city which is present in folder country.city.txtcatThis command concatenates and ...
Read MoreLoading and Removing Kernel Module
The Linux kernel modules can be loaded or removed from the kernel as required. This can be done without recompiling the kernel or rebooting the system and it enhances the functionality of the system.Without the kernel modules, the operating system would have to include all the systems that provide all anticipated functionalities in the base kernel. This would lead to wastage of memory as most of those systems would not be used often. Also, the users would need to rebuild and reboot the base kernel every time they would require a new functionality.The kernel modules have a .ko extension and ...
Read MoreAdvantages of using Loadable Kernel Modules
Loadable kernel modules in an operating system is an object file that contains code to extend the running kernel, which is also known as the base kernel. The loadable kernel modules are used to add support for file systems, hardware, system calls etc.A figure that shows the loadable modules of the operating system is as follows −Advantage of Loadable Kernel ModulesAn operating system would have to include all the systems that provided all anticipated functionalities in the base kernel if there were no loadable modules. This would lead to wastage of memory as most of those systems would not be ...
Read MoreSystem Calls in Unix and Windows
The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers.Unix System CallsSystem calls in Unix are used for file system control, process control, interprocess communication etc. Access to the Unix kernel is only available through these system calls. Generally, system calls are similar to function calls, the only difference is that they remove the control from the user process.There are around 80 system calls in the Unix interface currently. Details about some of ...
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