shell Archives - Complete, Concrete, Concise

Ubuntu 13.04 – How to Run a Shell / Command Line / Terminal as root

richardsplanet — Wed, 01 May 2013 04:06:59 +0000

This tutorial is for Ubuntu 13.04.

It is probably the same for other versions of Ubuntu and (probably) most other Linux distributions, but no guarantee is made.

Detailed instructions for opening a command line / terminal can be found here.

When you open a terminal in Ubuntu, you do not have administrative privileges. This means that there are some operations you cannot perform at the terminal.

Ubuntu provides the sudo command which temporarily grants you administrative privilege. However, you still have to type sudo before each administrative command you want to perform.

If you want to live dangerously and have full root access while at the terminal, enter the following command in the terminal:

sudo bash

After entering your password, you now be running with full root privilege at the command line:

Note: in order for this to work, you need to be a user who has the right to run sudo. In general, most users of Ubuntu have this right. However, user accounts can be created that do not have this right.

How it Works

Because some commands are potentially dangerous, unless you are root you are not allowed to run them. Using the sudo command temporarily elevates your status to root and allows you to run these commands.

When you run a terminal, it has the same privilege as the current user.

By running sudo bash you start another copy of the bash shell. However, you because you started it with sudo it runs with root privilege.

What is commonly called a terminal or command line is, in fact, a shell. There are many types of shells, bash is the default one with Ubuntu.

WARNING: running as root is a good way to mess up your system if you are not careful because there are no checks in place to prevent you from making catastrophic changes to your system.

I grant that by using the sudo command you can also irretrievably damage your system, but at least you had to type sudo (and possibly a password) before doing anything.

The post Ubuntu 13.04 – How to Run a Shell / Command Line / Terminal as root appeared first on Complete, Concrete, Concise.

Ubuntu 13.04 – Basic Command Line Techniques

richardsplanet — Tue, 30 Apr 2013 19:59:01 +0000

This tutorial is for Ubuntu 13.04.

It is probably the same for every other version of Ubuntu and all other Linux distros, but I make no guarantee.

Linux (on which Ubuntu is based) is fundamentally a command line driven operating system. While there are graphical interfaces to many of the available commands, sometimes you need (or have no choice) to work at the command line.

There are five fundamental things everyone working at the command line should know (or at least be aware of):

man
pipes
redirection
less (or more)
ls

man

man is short for manual

man is the help file.

When you want to know more about a command, you enter man to display information about the command. For example:

man ls

will bring up the man page for the command ls. You could also enter man man to display information about the man command. The man page for ls looks something like this:

To navigate through a man you use the following commands:

q – exit (quit) the man page
SPACE or f – forward to the next page
b – backward to the previous page
e – forward one line
y – backward one line

While there are man pages for pretty much every command, there is no man page for the command cd.

Pipes

Pipes allow you to send the displayed output from one command to another command.

In other words, when you enter a command that displays a bunch of information on the terminal (and maybe scrolls past the top of the terminal), you can use a pipe to send that information to another command.

The most common use of pipes is with the more (or, preferably, less) command. This is especially true when information scrolls past the top of the terminal.

The pipe is the vertical bar (or broken bar) symbol: ‘|‘.

For example, any of the following commands is likely display information that will scroll past the top of the terminal:

ls /bin
ls /etc
ls /lib

If we pipe the output to the more command, then we can scroll through the output one display page at a time:

ls /etc | more

Another common use of pipes is with the grep command. (grep is often used to filter out unwanted information – but I won’t be covering grep here.)

You can pipe together as many commands as you like. The output from the command on the left of the pipe is sent to the command on the right of the pipe.

Redirection

Sometimes you need to capture the information displayed by a command. This is done using redirection.

The output displayed by a command can be sent to a file instead of the display.

The redirection operator is the greater than symbol: ‘>’.

For example, suppose I want to dump a man page to file, so I can later look at (or print that file). I can do so by redirecting the man output to a file (you choose the name of the file):

man ls > ls.txt

The above command will send the output of the man page for ls to a file called ls.txt. I can then handle ls.txt the same way I handle any text file.

Another example, I could send a directory listing to a file as well:

ls > directory_list

The above command will send the output of ls to a file called directory_list. Again, the file can be handled the same way any other text file is handled.

Redirection always send stores the file in the current directory (normally, this will be your /home/ directory). You can write the file to another directory by either (1) changing to a different directory (using the cd command), or (2) specifying the path along with the file name. Note: you may not have permission to write in other directories, so the operation will fail.

less

less is an improved version of the more command. The main advantage of using less instead of more is that less lets you scroll backwards through data that has been piped to it; more only allows you to scroll forward through piped data. Other than that difference, less and more behave almost identically.

less is used to display information one page at a time.

Most often it is used in conjunction with pipes to prevent output from scrolling off the top of the terminal:

ls | less

less can be used to display the contents of a text file:

less

where is the name of the text file to display.

To navigate through text being displayed by less you use the following commands:

q – exit (quit) less
SPACE or f – forward to the next page
b – backward to the previous page (does not work if more is displaying text from a pipe and the main reason why less is preferred)

ls

ls is short for list

ls is used to display the contents of a directory.

Directory contents are colour coded. Different files have different colours.

The default colours (in the default Ubuntu 13.04 terminal) for common file types are:

Note: if you or someone has configured your system, or you are using a different terminal (or a different Linux distribution), the colours and their significance may be completely different.

There are other colour combinations in use and some colours (notably purple) are reused for other file types.

The post Ubuntu 13.04 – Basic Command Line Techniques appeared first on Complete, Concrete, Concise.

Ubuntu 13.04 – How to get a Command Line, Shell, or Terminal

richardsplanet — Thu, 25 Apr 2013 07:01:15 +0000

These instructions are for Ubuntu 13.04 using the Unity interface (although, hints are provided at the bottom of the article for those who have installed a different desktop).

Linux (of which Ubuntu is a flavour) and it’s inspiration Unix, have a strong emphasis and tradition of doing everything via typed commands.

Often, when searching the Internet for a solution to a problem, you often find terse (possibly cryptic) answers along the lines of:

Test if you can reach Google with ping -c 4 google.com

To recursively change your file permissions just: chmod 755 -R /opt/lampp/htdocs

In order to run those commands, you have to open a shell or command line or terminal (they are all synonymous, but shell is the preferred term in Linux and Unix circles).

There are many different shells, the original Unix shell is called the Bourne Shell (or sh), then came the C Shell (csh) and Korn Shell (ksh). Linux tends to use the Bourne Again Shell (bash). For the most part, they all do the same thing, so you don’t need to worry about which one you are using.

If you want to know which shell you are using, just enter echo $SHELL at the command line and press Enter.

Note: If you find a command line solution / trick / tip for a non-Ubuntu Linux distribution, there is a good chance (though not 100% guaranteed) that it might work with Ubuntu.

If you get a Permission denied or Are you root? response when you type in the command, try prefixing the command with sudo. Ubuntu requires administrator level privileges for certain commands. sudo temporarily gives administrator privileges (after you supply your password).

Opening a Terminal using a Keyboard Shortcut

This is the default keyboard shortcut for Ubuntu 13.04 (and probably most Linux distros running a GNOME 3 based desktop), unless you (or someone else) has changed it, it should work.

This also the default keyboard shortcut if you have changed your desktop environment to GNOME Shell, LXDE, or the Lubuntu Desktop and will work unless you (or someone else) has changed it.

This will NOT work for the XFCE or Xubuntu Desktop unless you (or someone else) has added the keyboard shortcut.

1) Press Ctrl + Alt + T to open a terminal / command line / shell.

Note: pressing Ctrl + Alt + T means: while holding down both the Ctrl key and Alt key, press the T key as though you intend to type it.

DO NOT press the Shift key because Ctrl + Alt + Shift + T is different from Ctrl + Alt + T.

It does NOT matter if your Caps Lock is on or off.

The terminal should look something like this:

Opening a Terminal from Unity

1) Click the Dash icon (or use the keyboard shortcut by tapping the Windows / Super key – don’t hold it down, just tap it as if you were going to type it):

2) Type terminal into the entry field:

As you type, Unity will display matching results below the entry field. You can stop typing when what you are looking for is the leftmost item.

3) Press Enter / Return key to open the terminal:

You can also open the terminal by clicking on it with your mouse.

You can use the arrow keys on your keyboard to navigate to it and then press the Enter key to select it (if you are using the arrow keys built into your numpad ensure that Num Lock is off):

Opening a Terminal if You are not Using Unity

Because there are many different types of desktops available for Linux, it is not possible to list all possible ways to start the terminal. However … the general technique is the same:

1) Open the Main Menu or Applications Menu (or whatever the main menu for your environment is called).

2) If you are lucky, there will be a menu entry for a terminal (it might be called Terminal or LXTerminal or something else with terminal in the name.

3) If you are unlucky, then you will have to look for it in a submenu. It is most likely to be found in a submenu called Accessories or System.

Note: You may have more than one terminal application installed or the terminal application may appear in more than one menu location.

How to (Almost) Always Get a Command Prompt

This works with pretty much any Linux distribution (unless they have been specially compiled to disable it).

If you need to access the command line and no terminal application has been installed, or you can’t find it, or the GUI has become unresponsive, you can press Ctrl + Alt + F1 to switch you to a full screen text terminal / command line / shell. To return to your GUI, press Ctrl + Alt + F7.

Note: pressing Ctrl + Alt + F1 means: while holding down both the Ctrl key and Alt key, press the F1 key as though you intend to type it.

The same is true when pressing Ctrl + Alt + F7.

It does NOT matter if your Caps Lock is on or off.

All Linux distributions (unless specially compiled otherwise), use Ctrl + Alt + F1 through Ctrl + Alt + F6 provide access to 6 full screen command line terminals. These 6 terminals are always available, so it doesn’t matter which one you access.

In the same way, Ctrl + Alt + F7 through Ctrl + Alt + F12 provide access to running X Servers. Normally, there is only one and it is found at Ctrl + Alt + F7 – unless you have additional X Servers running, F8 through F12 will be blank screens.

You will be required to login with your username and password (as with all command lines, your password is not echoed back to you):

Otherwise, it behaves exactly like any other terminal.

The post Ubuntu 13.04 – How to get a Command Line, Shell, or Terminal appeared first on Complete, Concrete, Concise.

Ubuntu 12.04 – How to Run a Shell / Command Line / Terminal with root Privilege / Access

richardsplanet — Wed, 13 Mar 2013 12:41:20 +0000

This tutorial is for Ubuntu 12.04.

It should be the same for other versions of Ubuntu and (probably) most other Linux distributions, but no guarantee is made./p>

Detailed instructions for opening a command line / terminal can be found here.

When you open a terminal in Ubuntu, you do not have administrative privileges. This means that there are some operations you cannot perform at the terminal.

Ubuntu provides the sudo command which temporarily grants you administrative privilege. However, you still have to type sudo before each administrative command you want to perform.

If you want to live dangerously and have full root access while at the terminal, enter the following command in the terminal:

sudo bash

After entering your password, you now be running with full root privilege at the command line:

How it Works

When you run a terminal, it has the same privilege as the current user.

By running sudo bash you start another copy of the bash shell. However, you because you started it with sudo it runs with root privilege.

What is commonly called a terminal or command line is, in fact, a shell. There are many types of shells, bash is the default one with Ubuntu.

WARNING: running as root is a good way to mess up your system if you are not careful because there are no checks in place to prevent you from making catastrophic changes to your system.

I grant that by using the sudo command you can also irretrievably damage your system, but at least you had to type sudo (and possibly a password) before doing anything.

The post Ubuntu 12.04 – How to Run a Shell / Command Line / Terminal with root Privilege / Access appeared first on Complete, Concrete, Concise.

Ubuntu 12.04 – Basic Command Line Techniques

richardsplanet — Thu, 13 Dec 2012 14:57:21 +0000

This tutorial is for Ubuntu 12.04.

It should be the same for every other version of Ubuntu and all other Linux distros, but I make no guarantee.

There are five fundamental things everyone working at the command line should know (or at least be aware of):

man
pipes
redirection
more
ls

man

man is short for manual

man is the help file.

When you want to know more about a command, you enter man to display information about the command. For example:

man ls

will bring up the man page for the command ls. You could also enter man man to display information about the man command. The man page for ls looks something like this:

To navigate through a man you use the following commands:

q – exit (quit) the man page
SPACE or f – forward to the next page
b – backward to the previous page
e – forward one line
y – backward one line

For some reason, there is no man page for the command cd.

Pipes

Pipes allow you to send the displayed output from one command to another command.

The most common use of pipes is with the more command. This is especially true when information scrolls past the top of the terminal.

The pipe is the vertical bar (or broken bar) symbol: ‘|‘.

For example, any of the following commands is likely display information that will scroll past the top of the terminal:

ls /bin
ls /etc
ls /lib

If we pipe the output to the more command, then we can scroll through the output one display page at a time:

ls /etc | more

Another common use of pipes is with the grep command. (grep is often used to filter out unwanted information – but I won’t be covering grep here.)

You can pipe together as many commands as you like. The output from the command on the left of the pipe is sent to the command on the right of the pipe.

Redirection

Sometimes you need to capture the information displayed by a command. This is done using redirection.

The output displayed by a command can be sent to a file instead of the display.<./p>

The redirection operator is the greater than symbol: ‘&gt’.

For example, suppose I want to dump a man page to file, so I can later look at (or print that file). I can do so by redirecting the man output to a file (you choose the name of the file):

man ls > ls.txt

The above command will send the output of the man page for ls to a file called ls.txt. I can then handle ls.txt the same way I handle any text file.

Another example, I could send a directory listing to a file as well:

ls > directory_list

The above command will send the output of ls to a file called directory_list. Again, the file can be handled the same way any other text file is handled.

more is used to display information one page at a time.

Most often it is used in conjunction with pipes to prevent output from scrolling off the top of the terminal:

ls | more

more can be used to display the contents of a text file:

more

where is the name of the text file to display.

To navigate through text being displayed by more you use the following commands:

q – exit (quit) more
SPACE or f – forward to the next page
b – backward to the previous page (does not work if more is displaying text from a pipe)

There is a slightly more useful command called less that allows you to scroll forwards and backwards through piped information. Aside from that difference less behaves very much like more.

You can use man less to learn about the less command

ls

ls is short for list

ls is used to display the contents of a directory.

Directory contents are colour coded. Different files have different colours.

The default colours (in the default Ubuntu 12.04 terminal) for common file types are:

There are other colour combinations in use and some colours (notably purple) are reused for other file types.

The post Ubuntu 12.04 – Basic Command Line Techniques appeared first on Complete, Concrete, Concise.

Ubuntu 12.10 – How to get a Command Line, Shell, or Terminal

richardsplanet — Thu, 18 Oct 2012 10:47:49 +0000

These instructions are for Ubuntu 12.10 using the Unity interface (although, hints are provided at the bottom of the article for those who have installed a different desktop).

Linux (of which Ubuntu is a flavour) and it’s inspiration Unix, have a strong emphasis and tradition of doing everything via typed commands.

Often, when searching the Internet for a solution to a problem, you often find terse (possibly cryptic) answers along the lines of:

Test if you can reach Google with ping -c 4 google.com

To recursively change your file permissions just: chmod 755 -R /opt/lampp/htdocs

In order to run those commands, you have to open a shell or command line or terminal (they are all synonymous, but shell is the preferred term in Linux and Unix circles).

If you want to know which shell you are using, just enter echo $SHELL at the command line and press Enter.

TIP: If you find a command line solution / trick / tip for a non-Ubuntu Linux distribution, there is a good chance (though not 100% guaranteed) that it might work with Ubuntu.

Opening a Terminal using a Keyboard Shortcut

This is the default keyboard shortcut for Ubuntu 12.10 (and probably previous Ubuntu releases) running the GNOME / Unity desktop, unless you (or someone else) has changed it, it should work.

This also the default keyboard shortcut if you have changed your desktop environment to GNOME Shell, LXDE, or the Lubuntu Desktop and will work unless you (or someone else) has changed it.

This will NOT work for the XFCE or Xubuntu Desktop unless you (or someone else) has added the keyboard shortcut.

1) Press Ctrl + Alt + T to open a terminal / command line / shell.

NOTE: pressing Ctrl + Alt + T means: simultaneously hold down the Ctrl key and Alt key, then press the T key as though you intend to type it.

DO NOT press the Shift key because Ctrl + Alt + Shift + T is different from Ctrl + Alt + T.

It does NOT matter if your Caps Lock is on or off.

The terminal should look something like this:

Opening a Terminal from Unity

1) Click the Dash icon (or use the keyboard shortcut by pressing the Windows key – don’t hold it down, just tap it as if you were going to type it):

2) Type terminal into the entry field:

3) Click on the terminal icon:

Alternately, you can navigate to the terminal icon by using the arrow keys on your keyboard (if you are using the arrow keys built into your numpad ensure that Num Lock is off) and then pressing the Enter key to select it.

Opening a Terminal if You are not Using Unity

Because there are many different types of desktops available for Linux, it is not possible to list all possible ways to start the terminal. However … the general technique is the same:

1) Open the Main Menu or Applications Menu (or whatever the main menu for your environment is called).

2) If you are lucky, there will be a menu entry for a terminal (it might be called Terminal or LXTerminal or something else with terminal in the name.

3) If you are unlucky, then you will have to look for it in a submenu. It is most likely to be found in a submenu called Accessories or System.

NOTE: You may have more than one terminal application installed or the terminal application may appear in more than one menu location.

How to (Almost) Always Get a Command Prompt

This works with pretty much any Linux distribution (unless they have been specially compiled to disable it).

NOTE: pressing Ctrl + Alt + F1 means: simultaneously hold down the Ctrl key and Alt key, then press the F1 key as though you intend to type it.

The same is true when pressing Ctrl + Alt + F7.

It does NOT matter if your Caps Lock is on or off.

In all Linux distributions (unless specially compiled otherwise), Ctrl + Alt + F1 through Ctrl + Alt + F6 provide access to 6 full screen command line terminals. These 6 terminals are always available, so it doesn’t matter which one you access.

In the same way, Ctrl + Alt + F7 through Ctrl + Alt + F12 provide access to running X Servers. Normally, there is only one and it is found at Ctrl + Alt + F7 – unless you have enabled additional X Servers to be running F8 through F12 will be blank screens.

You will be required to login with your username and password (as with all command lines, your password is not echoed back to you):

Otherwise, it behaves exactly like any other terminal.

The post Ubuntu 12.10 – How to get a Command Line, Shell, or Terminal appeared first on Complete, Concrete, Concise.

Ubuntu 12.04 – How to get a Command Line, Shell, or Terminal

richardsplanet — Thu, 26 Apr 2012 08:00:00 +0000

These instructions are for Ubuntu 12.04 using the Unity interface (although, hints are provided at the bottom of the article for those who have installed a different desktop).

Linux (of which Ubuntu is a flavour) and it’s inspiration Unix, have a strong emphasis and tradition of doing everything via typed commands.

Often, when searching the Internet for a solution to a problem, you often find terse (possibly cryptic) answers along the lines of:

Test if you can reach Google with ping -c 4 google.com

To recursively change your file permissions just: chmod 755 -R /opt/lampp/htdocs

In order to run those commands, you have to open a shell or command line or terminal (they are all synonymous, but shell is the preferred term in Linux and Unix circles).

If you want to know which shell you are using, just enter echo $SHELL at the command line and press Enter.

TIP: If you find a command line solution / trick / tip for a non-Ubuntu Linux distribution, there is a good chance (though not 100% guaranteed) that it might work with Ubuntu.

For more information on using a command line, see this tutorial on Basic Command Line Techniques.

Opening a Terminal using a Keyboard Shortcut

This is the default keyboard shortcut for Ubuntu 12.04 (and probably previous Ubuntu releases) running the GNOME / Unity desktop, unless you (or someone else) has changed it, it should work.

This also the default keyboard shortcut if you have changed your desktop environment to GNOME Shell, LXDE, or the Lubuntu Desktop and will work unless you (or someone else) has changed it.

This will NOT work for the XFCE or Xubuntu Desktop unless you (or someone else) has added the keyboard shortcut.

1) Press Ctrl + Alt + T to open a terminal / command line / shell.

NOTE: pressing Ctrl + Alt + T means: simultaneously hold down the Ctrl key and Alt key, then press the T key as though you intend to type it.

DO NOT press the Shift key because Ctrl + Alt + Shift + T is different from Ctrl + Alt + T.

It does NOT matter if your Caps Lock is on or off.

The terminal should look something like this:

Opening a Terminal from Unity

1) Click the Dash icon (or use the keyboard shortcut by pressing the Windows key – don’t hold it down, just tap it as if you were going to type it):

2) Type terminal into the entry field:

3) Click on the terminal icon:

Opening a Terminal if You are not Using Unity

Because there are many different types of desktops available for Linux, it is not possible to list all possible ways to start the terminal. However … the general technique is the same:

1) Open the Main Menu or Applications Menu (or whatever the main menu for your environment is called).

2) If you are lucky, there will be a menu entry for a terminal (it might be called Terminal or LXTerminal or something else with terminal in the name.

3) If you are unlucky, then you will have to look for it in a submenu. It is most likely to be found in a submenu called Accessories or System.

NOTE: You may have more than one terminal application installed or the terminal application may appear in more than one menu location.

The post Ubuntu 12.04 – How to get a Command Line, Shell, or Terminal appeared first on Complete, Concrete, Concise.