Linux command line only

Basic structure and concepts

The first thing that you should notice is something like:

dud@shadowplay:~ $ or [dud@shadowplay ~]$

What you see here is called the prompt. It signifies that the computer is ready and awaiting user input. In my case, dud is the user that I’m logged in as. shadowplay is the computer’s hostname, and ~ is the current directory (the user’s home directory).

• A terminal is a «physical» (direct) interface to your Linux Operating System.
• A terminal emulator is what we’ll be using here. This is a CLI wrapped within your running GUI. Any applications running in a terminal emulator will be killed if you close the terminal emulator.
• A shell is an interpreter for commands entered into the terminal.
• A command is usually a small utility that the shell will execute for you.
• Output is what a command returns; most often this is returned on the terminal.
• Input consists of the arguments or data that any given command will take. Input will change the way a given command acts.
• A process is a running application on your computer. It can be active, sleeping, or in a number of other states.

Command Syntax

This section will try to give you a good rundown of the basic usage for the bash shell, which is the default user shell in Ubuntu.

Single Command

The command syntax will vary with each command. Here are some of the basics.

dud@shadowplay:~ $ ls file1.txt file2.pdf file3.mp3 file1.pdf another_file.txt Yet-Another_file.txt file-with_other-NAME.TXT

dud@shadowplay:~ $ cat file1.txt Roses are red. Violets are blue, and you have the bird-flu!

dud@shadowplay:~ $ ls -r file-with_other-NAME.TXT Yet-Another_file.txt another_file.txt file1.pdf file3.mp3 file2.pdf file1.txt

Multiple Commands

Sometimes the desired task may require the use of more than one command to be completed. Here is the syntax for the use of multiple commands.

dud@shadowplay:~ $grep red file1.txt ; grep blue file1.txt Roses are red, Violets are blue,

dud@shadowplay:~ $ grep red file1.txt && grep blue file1.txt Roses are red, Violets are blue, dud@shadowplay:~ $ grep purple file1.txt && grep blue file1.txt dud@shadowplay:~ $

dud@shadowplay:~ $ grep red file1.txt || grep blue file1.txt Roses are red, dud@shadowplay:~ $ grep purple file1.txt || grep blue file1.txt Violets are blue, dud@shadowplay:~ $

In the example above, you will notice command2 was only executed when command1 failed.

Wildcards

Wildcards are a useful feature that allows an unknown value or values to be used with another command. This becomes very useful with commands such as «ls» allowing only a range of filenames to be displayed.

There are three operators used with wildcards — «*», «?» and «[x-y]».

Specifing a single character

The «?» is used to represent a single unknown character, consider we have a folder containing four files: file1.pdf, file2.pdf, file2.mp3 and file23.pdf. If wanted to know which PDF filenames contained numbers, then we could use:

dud@shadowplay:~ $ ls file?.pdf file1.pdf file2.pdf

Specifying multiple characters

Using the same files as the previous example, if we wanted to search for all files called «file2» of any type we could:

dud@shadowplay:~ $ ls file2.* file2.pdf file2.mp3

Specifying a range

If we wanted to know all PDF filenames beginning with «file» and a number between 2 and 23 then we use:

dud@shadowplay:~ $ ls file12.pdf file2.pdf file23.pdf

Control Flow

Commands read input from the keyboard (standard input, or stdin) and write to output (standard out, or stdout). There is also a special output category for error messages called standard error (or stderr). These three locations are created automatically for each program.

We can redirect input and output to and from a command.

Redirection

dud@shadowplay:~ $ ls > file4.txt dud@shadowplay:~ $ cat file4.txt file1.txt file2.pdf file3.mp3 file1.pdf another_file.txt Yet-Another_file.txt file-with_other-NAME.TXT file4.txt

dud@shadowplay:~ $ ls >> file4.txt dud@shadowplay:~ $ cat file4.txt file1.txt file2.pdf file3.mp3 file1.pdf another_file.txt Yet-Another_file.txt file-with_other-NAME.TXT file4.txt file1.txt file2.pdf file3.mp3 file1.pdf another_file.txt Yet-Another_file.txt file-with_other-NAME.TXT file4.txt

In the example, you will notice the file was appended with the new information.

But bash takes it even further. You will have noticed that ls can produce error messages if a directory ls is suppose to list does not exist or the user lacks access rights. In bash, Error messages and the «regular results» (i.e. dir listing) are 2 separate streams. To ease use of results only find a detailed explanation of bash.

dud@shadowplay:~ $ sort another_file.txt another_file.txt file1.txt file1.txt file2.pdf file2.pdf file3.mp3 file3.mp3 file4.txt file4.txt file-with_other-NAME.TXT file-with_other-NAME.TXT Yet-Another_file.txt Yet-Another_file.txt

As you can see from this example, we used the file4.txt as input into the sort command.

Pipe

dud@shadowplay:~ $ ls | sort another_file.txt file1.pdf file1.txt file2.pdf file3.mp3 file-with_other-NAME.TXT Yet-Another_file.txt

The above example is using the output from ls as input to the sort command. You will notice the list has been sorted.

As you can see, the command line is an easy and powerful way of completing many tasks. If you want more information on using the command line, then look at the further reading section of this document.

Further reading

• UsingTheTerminal
• BasicCommands has a list of basic commands.
• AdvancedCommandlineHowto has some advanced command line features such as scripting.

CommandlineHowto (последним исправлял пользователь ckimes 2017-09-11 20:21:18)

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Is there a mininal, command-line-only distribution of Ubuntu or similar that runs within MS Windows

Ideally I’d like to click a shortcut on the Windows desktop and have a Linux shell appear in a command-prompt-style window. Obviously performance is unimportant since I assume a filesystem-within-a-filesystem is going to be slow.

I’ve found distros like PortableUbuntu and PenDriveLinux, but they all seem to be either out-of-date, minimally-supported, or too large.

Is there anything like that out there?

5 Answers 5

You might find that something like coLinux or andLinux might be slightly lighter but personally, I’d choose a VirtualPC/VirtualBox/VMWare virtual machine every time.

The problem with the xming-style native builds of Linux distributions is they’re very non-standard. They’re hacks to serve a purpose. They might fit your purpose but I prefer to have standard things available. With a VM you can port to a proper bare-metal install if the need ever arises.

If you are only looking to run some Linux commands, you may want to try Cygwin . Cygwin, it is a Unix/Linux environment for Windows that can be used to have all that tools that windows lacks: bash, sed, awk, grep, vi, tail, ps, and many more. Once installed it will provide a shortcut that opens a terminal with a bash prompt. It also has an X-server environment if you need it. I’ve been using it for a few years now and it makes my live easier in Windows.

Sounds to me like you should look into VMWare — as for a «minimal, command-line-only distribution», take a look at Ubuntu Server.

VMWare is an option certainly, and a server version is exactly what I had in mind. just wondered whether there was a hybrid system out there.

As for interfacing with it, Ubuntu server will present a command line through VMWare/Virtualbox’s interface or you can install a SSH server on Ubuntu and use Putty

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