The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How do I open a terminal? Asked 9 years, 2 months ago. Active 9 years, 2 months ago. Viewed k times. Improve this question. Community Bot 1. Amazingly, I don't think this is a duplicate question. Wow — Jjed. I was using a different version last week that had a nice little icon on the top of the screen that just launched it.
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Other Collection and Use of Information Application and System Logs Pearson automatically collects log data to help ensure the delivery, availability and security of this site. In this case, however, we do mean to. The addition of options to our rm or rmdir commands will let us perform dangerous actions without the aid of a safety net! In the case of rmdir we can add a -p switch to tell it to also remove the parent directories. Think of it as the counterpoint to mkdir -p.
It still follows the normal rmdir rules of only deleting empty directories though, so if there was also a file in dir1 , for example, only dir3 and dir2 would get removed. Instead it deletes them totally, utterly and irrevocably. Yet still text prevails as a means to organise and categorise files. How many lines are there in your combined. The wc w ord c ount command can tell us that, using the -l switch to tell it we only want the line count it can also do character counts and, as the name suggests, word counts :.
Similarly, if you wanted to know how many files and folders are in your home directory, and then tidy up after yourself, you could do this:. That method works, but creating a temporary file to hold the output from ls only to delete it two lines later seems a little excessive. Fortunately the Unix command line provides a shortcut that avoids you having to create a temporary file, by taking the output from one command referred to as standard output or STDOUT and feeding it directly in as the input to another command standard input or STDIN.
This process of piping one command into another is so commonly used that the character itself is often referred to as the pipe character, so if you see that term you now know it just means the vertical bar. If we wanted to list them all it would clearly fill up more than a single screen. Going back to our own files, we know how to get the number of lines in combined.
Unix has a command, uniq , that will only output unique lines in the file. So we need to cat the file out and pipe it through uniq. But all we want is a line count, so we need to use wc as well. If your file is very long, you might want to pipe it through less to make it easier to inspect:.
It appears that very few, if any, of our duplicate lines are being removed. To understand why, we need to look at the documentation for the uniq command.
Most command line tools come with a brief and sometimes not-so-brief instruction manual, accessed through the man man ual command. The format of man pages is often terse, think of them more as a quick overview of a command than a full tutorial. The uniq man page is a typical example in that it starts with a brief one-line description of the command, moves on to a synopsis of how to use it, then has a detailed description of each option or parameter.
But whilst man pages are invaluable, they can also be inpenetrable. The question, then, is how to rearrange the lines in our file so that duplicate entries are on adjacent lines. If we were to sort the contents of the file alphabetically, that would do the trick. Unix offers a sort command to do exactly that. We can finally complete our task of counting the unique lines in the file:. As you can see, the ability to pipe data from one command to another, building up long chains to manipulate your data, is a powerful tool, as well as reducing the need for temporary files, and saving you a lot of typing.
Many manuals Most Linux command line tools include a man page. One good reason for learning some command line basics is that instructions online will often favour the use of shell commands over a graphical interface. The superuser is, as the name suggests, a user with super powers. As for those super powers: root can modify or delete any file in any directory on the system, regardless of who owns them; root can rewrite firewall rules or start network services that could potentially open the machine up to an attack; root can shutdown the machine even if other people are still using it.
In short, root can do just about anything , skipping easily round the safeguards that are usually put in place to stop users from overstepping their bounds. Of course a person logged in as root is just as capable of making mistakes as anyone else. The annals of computing history are filled with tales of a mistyped command deleting the entire file system or killing a vital server. Despite that, human nature being what it is, many administrators over the years have been guilty of using root as their main, or only, account.
In an effort to reduce these problems many Linux distributions started to encourage the use of the su command. When used with no arguments it assumes you want to change to the root user hence the first interpretation of the name , but you can pass a username to it in order to switch to a specific user account the second interpretation. By encouraging use of su the aim was to persuade administrators to spend most of their time using a normal account, only switch to the superuser account when they needed to, and then use the logout command or Ctrl-D shortcut as soon as possible to return to their user-level account.
By minimising the amount of time spent logged in as root , the use of su reduces the window of opportunity in which to make a catastrophic mistake. In that respect su was only a small step forward for security. If you are asked to use su with a username then if you have the password you will have access to all the files of that user, and could accidentally delete or modify them.
When using su your entire terminal session is switched to the other user. Better to disable the root account entirely and then, instead of allowing long-lived terminal sessions with dangerous powers, require the user to specifically request superuser rights on a per-command basis.
A configuration file is used to define which users can use sudo , and which commands they can run. On a Ubuntu system the first user created when the system is installed is considered to be the superuser. When adding a new user there is an option to create them as an administrator, in which case they will also be able to run superuser commands with sudo.
In this screenshot of Ubuntu Be careful with sudo If you are instructed to run a command with sudo , make sure you understand what the command is doing before you continue. Running with sudo gives that command all the same powers as a superuser.
You can use full paths to folders or simply the name of a folder within the directory you are currently working. Some common uses are:. You can also rename files by moving them to the directory they are currently in, but under a new name. You can specify where you want the directory created — if you do not do so, it will be created in your current working directory.
Some uses are :. This command is a third alternative to get help. While not as detailed as the info or man pages, this will provide a quick overview of the command and its uses. What you have to do is run the below command, where is the username whose password has to change:. Thank you so much.
Am an Ubuntu beginner and hopes it may help me to start my Terminal lessons…. Superb great work.. I get very powerful information on this website related to ubuntu. I have started ubuntu, therefore, I should more information related to ubuntu commands.
Thank you. I am brand spanking new to Linux and need an even more basic intro than what is presented here. I know what I want to do, but am having a hard time finding a resource for Ubuntu beginners that literally starts at the ground floor. Save my name, email, and website in this browser for the next time I comment.
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