Linux: Symbolically Linking Files

scottalanmiller

If I go to /var/log I can see the Link file created before.

Hmmm... nothing should have been created in there. Which file appeared in there?

iroal

It's Centos 7, spanish. let my know if you need any test.

scottalanmiller

Ah yes, you have discovered a typo in my copying over from one system to the other. The linking command should have been...

# ln -s /var/log mydir

iroal

@scottalanmiller

It works, thaks you.

scottalanmiller

@iroal said:

@scottalanmiller

It works, thaks you.

Thanks for being an early adopter and proof reading my code for me!

alex.olynyk

I created a soft link to /etc/firewalld/zones/public.xml and called it 'fw'

But 'fw' is only available from the root directory.

How can I make 'fw' available from anywhere on the system?

scottalanmiller

@alex.olynyk said:

I created a soft link to /etc/firewalld/zones/public.xml and called it 'fw'

But 'fw' is only available from the root directory.

How can I make 'fw' available from anywhere on the system?

Well a couple of options. But you are kind of thinking of fw as an alias not as a symbolic link.

If you wanted a symbolic link that was really handy, you could make it directly under the /. So...

ln -s /etc/firewalld/zones/public.xml /fw

Then to look at that file you could do...

cat /fw
less /fw

Like that.

But likely what you actually want is an alias. What do you want to do with that file? Edit it? If so, use your editor of choice (mine is vi and we will cover why in a later lesson) you could do this...

alias fw="vi /etc/firewalld/zones/public.xml"

Then when you run fw it opens the file instantly for editing.

fw

BRRABill

Not quite thinking what I was doing, I was trying to forward my /var/log to another folder without delete the original first. Duh.

Anyway, I ran this command:

ln -s /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs /var/log

And what it did was put a folder called "xenserverlogs" into the /var/log folder

Why did it do that?

scottalanmiller

@BRRABill said in Linux: Symbolically Linking Files:

Not quite thinking what I was doing, I was trying to forward my /var/log to another folder without delete the original first. Duh.

Anyway, I ran this command:
ln -s /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs /var/log
And what it did was put a folder called "xenserverlogs" into the /var/log folder

Why did it do that?

The format is ln -s existingfile linklocation

So you designated /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs as the existing file. And you told it to make a symbolic link in the /var/log directory. Since /var/log already existed and you didn't specify the name of the symbolic link it had no choice but to use the default which is the "same as the original" which was xenserverlogs. So it created a link from /var/log/xenserverlogs to the file /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs.

And be sure to never use a term like "forward" in conjunction with links, that's a very different concept and does not apply here. That will just confuse you.

BRRABill

@scottalanmiller said

So you designated /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs as the existing file. And you told it to make a symbolic link in the /var/log directory. Since /var/log already existed and you didn't specify the name of the symbolic link it had no choice but to use the default which is the "same as the original" which was xenserverlogs. So it created a link from /var/log/xenserverlogs to the file /run/sr-mount/da71e8e4-27b9-f51d-3390-93793b0a2bfd/xenserverlogs.

And be sure to never use a term like "forward" in conjunction with links, that's a very different concept and does not apply here. That will just confuse you.

So to confirm, if I had first removed the /var/log folder, that command would have worked as I wanted it to, correct?

scottalanmiller

@BRRABill said in Linux: Symbolically Linking Files:

So to confirm, if I had first removed the /var/log folder, that command would have worked as I wanted it to, correct?

Correct. Since /var/log is a mount point for you, though, that is not as simple as deleting or renaming. You have to stop it mounting first. Then you can rmdir /var/log. Then you can symlink.