Shell what is

Alternatively, you can reset your original prompt by exiting the shell and opening a new session. This is up to you! The dollar sign is a prompt , which shows us that the shell is waiting for input; your shell may use a different character as a prompt and may add information before the prompt. When typing commands, either from these lessons or from other sources, do not type the prompt, only the commands that follow it.

At any moment, our current working directory is our current default directory, i. The command to change locations in our file system is cd , followed by a directory name to change our working directory.

We can use the following command to get there:. To find out what they are, we can type:. It is a powerful resource to explore bash commands, understand their usage and flags.

Some manual files are very long. When you are done reading, hit q to quit. Use the -l option for the ls command to display more information for each item in the directory. The additional information given includes the name of the owner of the file, when the file was last modified, and whether the current user has permission to read and write to the file.

Some Linux distributions install several. These might include gnome-terminal , konsole , xterm , rxvt , kvt , nxterm , and eterm. Window managers usually have a way to launch a terminal from the menu. Look through the list of programs to see if anything looks like a terminal emulator.

While there are a number of different terminal emulators, they all do the same thing. They give us access to a shell session. You will probably develop a preference for one, based on the different bells and whistles it provides. OK, let's try some typing. Bring up a terminal window. The first thing we should see is a shell prompt that contains our user name and the name of the machine followed by a dollar sign. Something like this:.

If all went well, we should have gotten an error message complaining that it cannot understand the command:. Shell reads your input after you press Enter. It determines the command you want executed by looking at the first word of your input.

A word is an unbroken set of characters. Spaces and tabs separate words. You can customize your command prompt using the environment variable PS1 explained in the Environment tutorial. The original Unix shell was written in the mids by Stephen R. Bourne shell was the first shell to appear on Unix systems, thus it is referred to as "the shell". For this reason, it is the shell of choice for writing scripts that can be used on different versions of Unix.

In this chapter, we are going to cover most of the Shell concepts that are based on the Borne Shell. In interactive mode, they accept input typed from the keyboard. When executing non-interactively, shells execute commands read from a file. A shell allows execution of GNU commands, both synchronously and asynchronously.

The shell waits for synchronous commands to complete before accepting more input; asynchronous commands continue to execute in parallel with the shell while it reads and executes additional commands. The redirection constructs permit fine-grained control of the input and output of those commands.