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Soft links question


 
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# 1  
Old 09-07-2015
Soft links question

Hello.

I have some main directories.
For example :
Code:
/main_dir1
/main_dir2

In main_dir2, I have a sub dir named sub_dir2-1 with 2 files in it ( file_2-1, file_2-2 )
Code:
/main_dir2
sub_dir2-1
file_2-1 file_2-2

From "/main_dir1/A/B/C" I make a soft link
Code:
ln  -s  /main_dir2/sub_dir2-1  /main_dir1/A/B/C/sub_dir2-1

Now every things below "/main_dir1/A/B/C/sub_dir2-1" are soft link is not it ?
Nothing are copied from "/main_dir2sub_dir2-1" to "/main_dir1/A/B/C/sub_dir2-1" ?
I ask because nothing show that "file_2-1" and "file_2-2" are soft link files.
Thank you for helping
# 2  
Old 09-07-2015
And rightly so. Those two files (and their entries) exist exactly once, but they are accessible by two paths, one of which has a soft link in it.
# 3  
Old 09-07-2015
Because "file_2-1" and "file_2-2" are NOT soft link files....
/main_dir1/A/B/C/sub_dir2-1 is the soft link...
when you type
Code:
 cd /main_dir1/A/B/C/sub_dir2-1

look what you see...
# 4  
Old 09-07-2015
Let me tell you a story ....

Once upon a time there was a house, located at /main_dir avenue. It was a big house, with apartments file1 and file2 and so on.

When mail came (you know "mail", yes? It is e-mail based on paper instead of electricity), it was addressed to /main_dir/1/file1, /main_dir/1/file2 or any of the other apartments. The "/1" came because it was the first house in /main_dir avenue. This was the list of tenants in the house:

Code:
# ls -l /main_dir/1
-rw------- 1 tenant house       0 Aug 28 18:54 file1
-rwxr-xr-- 1 tenant house     355 Aug 25 02:15 file2
-rwxrwxrwx 1 tenant house     804 Aug 22 11:32 file3
-rw-r--r-- 1 tenant house 1226240 Aug 23 16:24 file4

But one day the owner of the house noticed that the house was not only located at /main_dir avenue. In fact it was located at the intersection of /main_dir avenue and and /softlink street. And because he wanted maximum comfort for his tenants he called the architect to build a second entry from /softlink street. An the architect went to work:

Code:
# ln -s /main_dir/1 /softlink/24

As you can see the new entry got number 24 at /softlink street. From this day on mail could be addressed o either /main_dir/1/file1 or /softlink/24/file1 because /main_dir/1 and /softlink/24 were different entries to the same building, but the apartment file1 was still the same, regardless of which entry you used to enter the building on your way to it.

And tomorrow, i will tell you another old story ..... ;-))

I hope this helps.

bakunin
These 4 Users Gave Thanks to bakunin For This Post:
# 5  
Old 09-07-2015
Quote:
Originally Posted by bakunin
Let me tell you a story ....

I hope this helps.

bakunin
I am afraid not, because english is not my mother language.

---------- Post updated at 22:32 ---------- Previous update was at 22:30 ----------

Quote:
Originally Posted by vbe
Because "file_2-1" and "file_2-2" are NOT soft link files....
/main_dir1/A/B/C/sub_dir2-1 is the soft link...
when you type
Code:
 cd /main_dir1/A/B/C/sub_dir2-1

look what you see...
I see two files.
And this my question : Are they soft link or a copy of original files into main_dir1/A/B/C/sub_dir2-1
# 6  
Old 09-07-2015
A link is a link, just like in Windows.

So when you enter the house at cd /softlink you actualy enter /main_dir, seeing the very same files.
Deleting a file in /softlink will also remove the file in /main_dir.

EDIT:
Or in other words, consider the /main_dir a house at a street cross.
If the house was only at one street, it would have just one door.
But since its sides are at two streets now with the symlink, it has two doors as well, which both are leading to the very same rooms (dirs and files) within the house/folder.

EDIT2:
The only 'non-original' file is the symlink /symlink, which represents a folder (/main_dir)
All other files are 'original'...

hth

Last edited by sea; 09-07-2015 at 05:51 PM..
# 7  
Old 09-07-2015
Quote:
Originally Posted by jcdole
[...]
Code:
ln  -s  /main_dir2/sub_dir2-1  /main_dir1/A/B/C/sub_dir2-1

Now every things below "/main_dir1/A/B/C/sub_dir2-1" are soft link is not it ?
Nothing are copied from "/main_dir2sub_dir2-1" to "/main_dir1/A/B/C/sub_dir2-1" ?
I ask because nothing show that "file_2-1" and "file_2-2" are soft link files.
Thank you for helping
Hello jcdole,

file_2-1 and file_2-2 are not soft links, they are original files living under the subdirectory /main_dir2/sub_dir2-1.
On the other hand
/main_dir1/A/B/C/sub_dir2-1 is a link (or another name) for the same subdirectory /main_dir2/sub_dir2-1.

If you delete /main_dir1/A/B/C/sub_dir2-1, you are just deleting the link or second name, but not /main_dir2/sub_dir2-1
If you delete the content inside /main_dir1/A/B/C/sub_dir2-1/* you are deleting the originalfile_2-1 and file_2-2, and they will be gone, as well, when you look into /main_dir2/sub_dir2-1
 

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