Editing Files - Linux

NOTES

Editing Files

There are several ways to edit a file. One of the most common text editors for this is Vi and Vim. More rarely, there is the Nano
editor. We will first deal with the Nano editor here, as it is a bit
easier to understand.
We can create a new file directly with the Nano editor by specifying the
file's name directly as the first parameter. In this case, we create a
new file named
notes.txt.
satvik@htb[/htb]$ nano notes.txt
Now we should see a so-called "pager" open, and we can freely enter or insert any text. Our shell should then look something like this.

Nano Editor
  GNU nano 2.9.3                                    notes.txt

Here we can type everything we want and make our notes.▓

{ #G}
Get Help
{ #O}
Write Out
{ #W}
Where Is
{ #K}
Cut Text
{ #J}
Justify
{ #C}
Cur Pos M-U Undo

{ #X}
Exit
{ #R}
Read File ^\ Replace
{ #U}
Uncut Text
{ #T}
To Spell
{ #_}
Go To Line M-E Redo


Below we see two lines with short descriptions. The `caret` (`^`) stands for our "`[CTRL]`" key.  
For example, if we press  
`[CTRL + W]`, a "`Search:`" line appears at the bottom of the editor, where we can enter the word or words we are looking for.  
If we now search for the word "  
`we`" and press `[ENTER]`, the cursor will move to the first word that matches.

```Plain
GNU nano 2.9.3                                    notes.txt

Here ▓we can type everything we want and make our notes.

Search:   notes

{ #G}
Get Help M-C Case Sens M-B Backwards M-J FullJstify
{ #W}
Beg of Par
{ #Y}
First Line
{ #P}
PrevHstory

{ #C}
Cancel M-R Regexp
{ #R}
Replace
{ #T}
Go To Line
{ #O}
End of Par
{ #V}
Last Line
{ #N}
NextHstory


To jump to the next match with the cursor, we press `[CTRL + W]` again and confirm with `[ENTER]` without any additional information.

```Plain
GNU nano 2.9.3                                    notes.txt

Here we can type everything ▓we want and make our notes.

Search [we]:

{ #G}
Get Help M-C Case Sens M-B Backwards M-J FullJstify
{ #W}
Beg of Par
{ #Y}
First Line
{ #P}
PrevHstory

{ #C}
Cancel M-R Regexp
{ #R}
Replace
{ #T}
Go To Line
{ #O}
End of Par
{ #V}
Last Line
{ #N}
NextHstory


Now we can save the file by pressing `[CTRL + O]` and confirm the file name with `[ENTER]`.

```Plain
GNU nano 2.9.3                                    notes.txt

Here we can type everything we want and make our notes.

File Name to Write: notes.txt▓

{ #G}
Get Help M-C Case Sens M-B Backwards M-J FullJstify
{ #W}
Beg of Par
{ #Y}
First Line
{ #P}
PrevHstory

{ #C}
Cancel M-R Regexp
{ #R}
Replace
{ #T}
Go To Line
{ #O}
End of Par
{ #V}
Last Line
{ #N}
NextHstory

After we have saved the file, we can leave the editor with `[CTRL + X]`.

### Back on the Shell

To view the contents of the file, we can use the command `cat`.

```Plain
satvik@htb[/htb]$ cat notes.txtHere we can type everything we want and make our notes.
There are many files on Linux systems that can play an essential role
for us as penetration testers whose rights have not been correctly set
by the administrators. Such files may include the file "
/etc/passwd".

VIM

Vim is an open-source editor for all kinds of ASCII
text, just like Nano. It is an improved clone of the previous Vi. It is
an extremely powerful editor that focuses on the essentials, namely
editing text. For tasks that go beyond that, Vim provides an interface
to external programs, such as
grep, awk, sed,
etc., which can handle their specific tasks much better than a
corresponding function directly implemented in an editor usually can.
This makes the editor small and compact, fast, powerful, flexible, and
less error-prone.

Vim follows the Unix principle here: many small specialized programs
that are well tested and proven, when combined and communicating with
each other, resulting in a flexible and powerful system.

Vim
satvik@htb[/htb]$ vim
  1 $
~
~                              VIM - Vi IMproved
~
~                               version 8.0.1453
~                           by Bram Moolenaar et al.
~           Modified by pkg-vim-maintainers@lists.alioth.debian.org
~                 Vim is open source and freely distributable
~
~                           Sponsor Vim development!
~                type  :help sponsor<Enter>    for information
~
~                type  :q<Enter>               to exit
~                type  :help<Enter>  or  <F1>  for on-line help
~                type  :help version8<Enter>   for version info
~

                                                                    0,0-1         All
In contrast to Nano, Vim is a modal editor that can
distinguish between text and command input. Vim offers a total of six
fundamental modes that make our work easier and make this editor so
powerful:

Mode Description

Normal In normal mode, all inputs are considered as editor commands. So
there is no insertion of the entered characters into the editor buffer,
as is the case with most other editors. After starting the editor, we
are usually in the normal mode.

Insert With a few exceptions, all entered characters are inserted into the buffer.

Visual The visual mode is used to mark a contiguous part of the text, which
will be visually highlighted. By positioning the cursor, we change the
selected area. The highlighted area can then be edited in various ways,
such as deleting, copying, or replacing it.

Command It allows us to enter single-line commands at the bottom of the
editor. This can be used for sorting, replacing text sections, or
deleting them, for example.

Replace In replace mode, the newly entered text will overwrite existing text
characters unless there are no more old characters at the current
cursor position. Then the newly entered text will be added.

When we have the Vim editor open, we can go into command mode by typing ":" and then typing "q" to close Vim.
  1 $
~
~                              VIM - Vi IMproved
~
~                               version 8.0.1453
~                           by Bram Moolenaar et al.
~           Modified by pkg-vim-maintainers@lists.alioth.debian.org
~                 Vim is open source and freely distributable
~
~                           Sponsor Vim development!
~                type  :help sponsor<Enter>    for information
~
~                type  :q<Enter>               to exit
~                type  :help<Enter>  or  <F1>  for on-line help
~                type  :help version8<Enter>   for version info
~
:q▓
Vim offers an excellent opportunity called vimtutor to
practice and get familiar with the editor. It may seem very difficult
and complicated at first, but it will only feel that way for a short
time. The efficiency we gain from Vim once we get used to it is
enormous.

VimTutor
satvik@htb[/htb]$ vimtutor
===============================================================================
=    W e l c o m e   t o   t h e   V I M   T u t o r    -    Version 1.7      =
===============================================================================

     Vim is a very powerful editor that has many commands, too many to
     explain in a tutor such as this.  This tutor is designed to describe
     enough of the commands that you will be able to easily use Vim as
     an all-purpose editor.

     The approximate time required to complete the tutor is 25-30 minutes,
     depending upon how much time is spent with experimentation.

     ATTENTION:
     The commands in the lessons will modify the text.  Make a copy of this
     file to practice on (if you started "vimtutor" this is already a copy).

     It is important to remember that this tutor is set up to teach by
     use.  That means that you need to execute the commands to learn them
     properly.  If you only read the text, you will forget the commands!

     Now, make sure that your Caps-Lock key is NOT depressed and press
     the   j   key enough times to move the cursor so that lesson 1.1
     completely fills the screen.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Mode	Description
`Normal`	In normal mode, all inputs are considered as editor commands. So there is no insertion of the entered characters into the editor buffer, as is the case with most other editors. After starting the editor, we are usually in the normal mode.
`Insert`	With a few exceptions, all entered characters are inserted into the buffer.
`Visual`	The visual mode is used to mark a contiguous part of the text, which will be visually highlighted. By positioning the cursor, we change the selected area. The highlighted area can then be edited in various ways, such as deleting, copying, or replacing it.
`Command`	It allows us to enter single-line commands at the bottom of the editor. This can be used for sorting, replacing text sections, or deleting them, for example.
`Replace`	In replace mode, the newly entered text will overwrite existing text characters unless there are no more old characters at the current cursor position. Then the newly entered text will be added.