nano Archives - Complete, Concrete, Concise

Ubuntu 13.04 – How to Change the Timout Period for sudo

richardsplanet — Wed, 01 May 2013 10:32:28 +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.

By default, sudo temporarily grants administrative privileges for 15 minutes. This means the first time you run sudo you will be prompted for your password. Then, for the next 15 minutes, you can run sudo without having to re-enter your password.

This should be fine for most users because the average user probably rarely drops to a command line to run an administrative command or two.

1) Open a terminal using Ctrl + Alt + T:

2) Enter the following command:

sudo visudo

3) Enter your password:

Note: when you type your password, nothing will happen on the screen. This is normal. As a security feature, Linux does not echo back any indication of the characters you are typing in.

This will bring up the sudo configuration file in the nano editor. Note: in other versions of Linux (or if Ubuntu has been modified), the configuration file may be opened with a different editor – in which case, you will need to Google for instructions on using that editor.

The command visudo does more than just open the sudo configuration file with the nano editor. It also checks to ensure the configuration file is correct (i.e. it will not let you edit the file and make it invalid). Note: you can still edit the file, so sudo becomes unusable, but the configuration file is (technically speaking) valid.

4) Locate the line Defaults (highlighted in yellow) and navigate to the end of it using the arrow / cursor keys on your keyboard (your mouse will not work). Add the following:

,timestamp_timeout=0

The number tells sudo for many minutes it should grant administrator privileges in this session.

A value of 0 tells sudo to always prompt for a password. Personally, this is the only setting that makes sense for me because if you are momentarily away from your computer, no one else can accidentally (or intentionally) run an administrative command while your sudo privilege is still active.

A positive number tells sudo to grant administrative privileges that that number of minutes. The number must be a whole number: 5, 15, 42, etc. Number like 3.1415 are not valid.

A negative number tells sudo to permanently grant administrative privileges during that session. The only use I see for this is if you want to have to type sudo before administrative commands, but not have to enter the password for subsequent commands.

5) Save your changes by pressing Ctrl + O:

You will be prompted to save the file as /etc/sudoers.tmp.

6) Press Enter to write the changes.

7) Observe that the changes were written:

8) Exit visudo by pressing Ctrl + X.

Starting a new command line session should pick up the changes you just made.

The post Ubuntu 13.04 – How to Change the Timout Period for sudo appeared first on Complete, Concrete, Concise.

Ubuntu 13.04 – Command Line Basics: Editing Files

richardsplanet — Wed, 01 May 2013 03:12:06 +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 work at the command line, from time to time, it may be necessary to edit files.

You can use an editor like gedit (the GUI based editor that comes with Ubuntu), however, by default, it will not permit you to edit system configuration files (which are likely the files you are trying to edit if you happen to be at the command line).

Starting gedit with Administrator Privileges

Enter the following command to start gedit with administrator privileges:

sudo gedit

Note: when you type your password, nothing will happen on the screen. This is normal. As a security feature, Linux does not echo back any indication of the characters you are typing in.

You should only be prompted to enter a password if you have not used the sudo command in the last 15 minutes or so.

You can also append the file you wish to open to the command. This will cause gedit to automatically open the file. For example:

sudo gedit history.log

Note: this will only work if the file is in the current directory. However, if you are at the command line, then you probably have navigated to the directory in question.

Editing with nano

Sometimes, you cannot use gedit because you have no graphical interface (GUI) – for example, you need to edit some x-server settings because you can’t get a graphical display, so you are exclusively at a command line.

While vi or one of its clones (vim, elvis, nvi, and vile to name some) tend to be the preferred text editor among Unix / Linux geeks – it is not the friendliest for casual (or one-off) users. The other major editor is emacs, but it is not installed by default in Ubuntu and it is not user friendly either.

nano is a clone of the pico editor.

To launch nano enter the command:

sudo nano

Note: It will also launch if you type in pico

As with gedit you can append the name of the file you want to edit to the command.

Using nano

nano is a simple editor that allows you to navigate through the text using the arrow keys on your keyboard.

At the bottom of the screen, there are two lines (highlighted in blue) that display a number of common commands.

The caret (^) symbol means Ctrl, as in, Ctrl + X. This means, “while holding down the Ctrl key, you press the other key as though you intend to type it”.

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

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

The most common commands you are likely to use are:

^X – (Ctrl + X) exit the editor
^O – (Ctrl + O) save / write the contents of the editor
^R – (Ctrl + R) open / read another file

If you decide to browse through the help (Ctrl + G), then be aware of the following:

^^ means Ctrl + ^ not Ctrl + Ctrl
M- means the Alt key. The Alt key is used the same way the Ctrl key is: it is held down while another key is typed. For example: M-\ means: while holding down the Alt key, press the \ key as though you intend to type it.
Some commands have parentheses around them, the parentheses are not to be typed. For example, (M-X) simply means Alt + X – the parentheses have nothing to do with it and should be ignored.

The post Ubuntu 13.04 – Command Line Basics: Editing Files appeared first on Complete, Concrete, Concise.

Ubuntu 12.04 – Command Line Basics: Editing Files

richardsplanet — Tue, 12 Mar 2013 18:06:57 +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.

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

When you work at the command line, from time to time, it may be necessary to edit files.

Normally, you can use an editor like gedit (the GUI based editor that comes with Ubuntu), however, by default, it will not permit you to edit system configuration files (which are likely the files you are trying to edit if you happen to be at the command line).

Starting gedit with Administrator Privileges

Enter the following command to start gedit with administrator privileges:

sudo gedit

Note: when you type your password, nothing will happen on the screen. This is normal. As a security feature, Linux does not echo back any indication of the characters you are typing in.

You should only be prompted to enter a password if you have not used the sudo command in the last 15 minutes or so.

You can also append the file you wish to open to the command. This will cause gedit to automatically open the file. For example:

sudo gedit history.log

Note: this will only work if the file is in the current directory. However, if you are at the command line, then you probably have navigated to the directory in question.

Editing with nano

nano is a clone of the pico editor.

To launch nano enter the command:

sudo nano

Note: It will also launch if you type in pico

As with gedit you can append the name of the file you want to edit to the command.

Using nano

nano is a simple editor that allows you to navigate through the text using the arrow keys on your keyboard.

At the bottom of the screen, there are two lines (highlighted in blue) that display a number of common commands.

The caret (^) symbol means Ctrl, as in, Ctrl + X. This means that while holding down the Ctrl key, you press the other key as though you intend to type it.

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

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

The most common commands you are likely to use are:

^X – (Ctrl + X) exit the editor
^O – (Ctrl + O) save / write the contents of the editor
^R – (Ctrl + R) open / read another file

If you decide to browse through the help (Ctrl + G), then be aware of the following:

^^ means Ctrl + ^ not Ctrl + Ctrl
M- means the Alt key. The Alt key is used the same way the Ctrl key is: it is held down while another key is typed. For example: M-\ means: while holding down the Alt key, press the \ key as though you intend to type it.
Some commands have parentheses around them, the parentheses are not to be typed. For example, (M-X) simply means Alt + X – the parentheses have nothing to do with it and should be ignored.

The post Ubuntu 12.04 – Command Line Basics: Editing Files appeared first on Complete, Concrete, Concise.