He took the name from the ed command string g/re/p, which translates as "global regular expression search. Thompson spent about an hour that evening making his tool a general utility that could be used by others and renamed it as grep. He needed a tool that could search for phrases and strings within text files. McMahon was trying to identify the authors of the Federalist papers through textual analysis. His department head at Bell Labs, Doug Mcilroy, approached Thompson and described the problem one of his colleagues, Lee McMahon, was facing. Ken Thompson had extracted the regular expression search capabilities from the ed editor ( pronounced ee-dee) and created a little program - for his own use - to search through text files. The first two are bang on the third is slightly off. Thirdly, it was written overnight to satisfy a particular need. Secondly, the wealth of options can be overwhelming. The grep command is famous in Linux and Unix circles for three reasons. It also works with piped output from other commands. Once the user is connected to a console, the shell displays the command prompt.The Linux grep command is a string and pattern matching utility that displays matching lines from multiple files. A user switches from one physical terminal to another using Alt + Fx from the command line or using CTRL + Alt + Fx. Virtual terminals are available within a graphical environment. Linux being multi-user, it is possible to connect several users several times, on different physical terminals (TTY) or virtual terminals (PTS). In Debian and other Debian-based systems like Ubuntu, PopOS, Linux Mint, we can find the list of all installed Kernels using dpkg command: dpkg -list grep linux-image. Find Installed Linux Kernels in Debian, Ubuntu, Linux Mint, PopOS. By default, at login, the login directory is selected as the current directory.Ī workstation-type installation (with graphical interface) starts this interface on terminal 1. As you can see, I have only one Linux Kernel in my Arch Linux system and its version is 5.9.14. It will contain the user's personal data and the configuration files of his applications. The user's login directory is by convention stored in the /home directory of the workstation. For various reasons, advanced Linux users can choose alternative shells such as the Korn Shell ( ksh), the C Shell ( csh), etc.
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