I tried to create a symbolic link to a non existing file
ln -s non_existing_file.txt $HOME/dir1/dir2/my_symbolic_link
Then I tried to write something in the non existing file using the symbolic link
vi $HOME/dir1/dir2/my_symbolic_link
Now after saving and exiting non_existing_file.txt is created under dir2.
Can someone explain why?
ln -s target linkpath
creates a symlink at linkpath which holds the name target. Operations on the symlink interpret the name target relative to the directory where the symlink resides, not the present working directory.
So, if you have a symlink holding, say, ../usr in /tmp/link-to-usr, then ls /tmp/link-to-usr will list the contents of /usr (which is /tmp/../usr) regardless of where the ls command is executed.
Related
I have a directory that contains media that I am trying to setup a basic symbolic link to - the directory is a mounted storage on a digital ocean droplet in the following directory /mnt/storage/media/all
this contains directories as shown below:
0118
0119
0218 and so on.......
I am trying to make a symlink from my unix terminal as follows :
$ root#server1:/var/www/abcd/public ln -s /mnt/storage/media/all
So if I cd into the public directory above I would expect to see the directories 0118, 0119, 0218 and so on... however when I cd into this directory I see the directory all and within this directories are the 0118, 0119, 0218 subdirectories.
How do I change the symbolic link so I see the directories 0118, 0119, 0218 etc.. and not the all directory (which contains those same sub directories)
Try giving a second argument for the function. Let that argument be the desired destination for the link (but it shouldn't exist prior to this).
E.g. ln -s /mnt/storage/media/all /var/www/abcd/public
In case the folder public already exists, the symlink will be created inside it.
I am having trouble symlinking dotfiles. I have a folder in my home directory ~/dotfiles which I have synced to a github repo. I am trying to take my .vimrc file in ~/dotfiles/.vimrc and create a symbolic link to put it at ~/.vimrc. To do this I type in
ln -s ~/dotfiles/.vimrc ~/.vimrc
But when I run that it says
ln: /Users/me/.vimrc: File exists
What am I doing wrong?
That error message means that you already have a file at ~/.vimrc, which ln is refusing to overwrite. Either delete the ~/.vimrc and run ln again or let ln delete it for you by passing the -f option:
ln -s -f ~/dotfiles/.vimrc ~/.vimrc
There is a better solution for managing dotfiles without using symlinks or any other tool, just a git repo initialized with --bare.
A bare repository is special in a way that they omit working directory, so you can create your repo anywhere and set the --work-tree=$HOME then you don't need to do any work to maintain it.
Approach
first thing to do is, create a bare repo
git init --bare $HOME/.dotfiles
To use this bare repo, you need to specify --git-dir=$HOME/.dotfiles/ and --work-tree=$HOME, better is to create an alias
alias dotfiles='/usr/bin/git --git-dir=$HOME/.dotfiles/ --work-tree=$HOME
At this point, all your configuration files are being tracked, and you can easily use the newly registered dotfiles command to manage the repository, ex :-
# to check the status of the tracked and untracked files
dotfiles status
# to add a file
dotfiles commit .tmux.conf -m ".tmux.conf added"
# push new files or changes to the github
dotfiles push origin main
I also use this way to sync and store my dotfiles, see my dotfiles repository and can read at Storing dotfiles with Git where I wrote about managing for multiple devices.
How to symlink all dotfiles in a directory recursively
Have a dotfiles directory that is structured as to how they should be structured at $HOME
dotfiles_home=~/dotfiles/home # for example
cp -rsf "$dotfiles_home"/. ~
-r: Recursive, create the necessary directory for each file
-s: Create symlinks instead of copying
-f: Overwrite existing files (previously created symlinks, default .bashrc, etc)
/.: Make sure cp "copy" the contents of home instead of the home directory itself.
Tips
Just like ln, if you want no headache or drama, use an absolute path for the first argument like the example above.
Note
This only works with GNU cp (preinstalled in Ubuntu), not POSIX cp. Check your man cp, you can install GNU coreutils if needed.
Thanks
To this and this.
So this doesn't seem like a terribly complicated question I have, but it's one I can't find the answer to. I'm confused about what the -p option does in Unix. I used it for a lab assignment while creating a subdirectory and then another subdirectory within that one. It looked like this:
mkdir -p cmps012m/lab1
This is in a private directory with normal rights (rlidwka). Oh, and would someone mind giving a little explanation of what rlidwka means? I'm not a total noob to Unix, but I'm not really familiar with what this means. Hopefully that's not too vague of a question.
The man pages is the best source of information you can find... and is at your fingertips: man mkdir yields this about -p switch:
-p, --parents
no error if existing, make parent directories as needed
Use case example: Assume I want to create directories hello/goodbye but none exist:
$mkdir hello/goodbye
mkdir:cannot create directory 'hello/goodbye': No such file or directory
$mkdir -p hello/goodbye
$
-p created both, hello and goodbye
This means that the command will create all the directories necessaries to fulfill your request, not returning any error in case that directory exists.
About rlidwka, Google has a very good memory for acronyms :). My search returned this for example: http://www.cs.cmu.edu/~help/afs/afs_acls.html
Directory permissions
l (lookup)
Allows one to list the contents of a directory. It does not allow the reading of files.
i (insert)
Allows one to create new files in a directory or copy new files to a directory.
d (delete)
Allows one to remove files and sub-directories from a directory.
a (administer)
Allows one to change a directory's ACL. The owner of a directory can always change the ACL of a directory that s/he owns, along with the ACLs of any subdirectories in that directory.
File permissions
r (read)
Allows one to read the contents of file in the directory.
w (write)
Allows one to modify the contents of files in a directory and use chmod on them.
k (lock)
Allows programs to lock files in a directory.
Hence rlidwka means: All permissions on.
It's worth mentioning, as #KeithThompson pointed out in the comments, that not all Unix systems support ACL. So probably the rlidwka concept doesn't apply here.
-p|--parent will be used if you are trying to create a directory with top-down approach. That will create the parent directory then child and so on iff none exists.
-p, --parents
no error if existing, make parent directories as needed
About rlidwka it means giving full or administrative access. Found it here https://itservices.stanford.edu/service/afs/intro/permissions/unix.
mkdir [-switch] foldername
-p is a switch, which is optional. It will create a subfolder and a parent folder as well, even if parent folder doesn't exist.
From the man page:
-p, --parents no error if existing, make parent directories as needed
Example:
mkdir -p storage/framework/{sessions,views,cache}
This will create subfolder sessions,views,cache inside framework folder irrespective of whether 'framework' was available earlier or not.
PATH: Answered long ago, however, it maybe more helpful to think of -p as "Path" (easier to remember), as in this causes mkdir to create every part of the path that isn't already there.
mkdir -p /usr/bin/comm/diff/er/fence
if /usr/bin/comm already exists, it acts like:
mkdir /usr/bin/comm/diff
mkdir /usr/bin/comm/diff/er
mkdir /usr/bin/comm/diff/er/fence
As you can see, it saves you a bit of typing, and thinking, since you don't have to figure out what's already there and what isn't.
Note that -p is an argument to the mkdir command specifically, not the whole of Unix. Every command can have whatever arguments it needs.
In this case it means "parents", meaning mkdir will create a directory and any parents that don't already exist.
for example, my directory like this:
lib
|
+--foo.so
+--bar.so -> bar.so.1.0.0.0
+--bar.so.1.0.0.0
Are these both ways always same?
The reason I ask this question is that I found unix will copy to real so file when I
cp -r lib /path/to/
new directory like this:
/path/to/lib
|
+--foo.so
+--bar.so
+--bar.so.1.0.0.0
The difference between so and ls -s is the difference between a file and a symbolic link. Symbolic links are like aliases to other files and operations on them result in changes in the linked files. When you do cp, it copies the linked file to the target directory with the link name as the file name, i.e., it reads the linked file when it opens the symbolic link to copy it. So lose the link and instead get a copy of the linked file. If you use -P option of the cp command you can preserve the symbolic link information.
cp -P lib /path/to/
I want to copy a complete directory content from /home/private_html/userx/ into the /home/private_html/usery/, the problem is that the directory userx contains few symlinks, and when using the cp it just skip them (skip occurs, if symlinks directs into a file, in case if it points into the directory, it just copy WHOLE directory instead...).
The command I was using looks following:
# cp -iprv /home/private_html/userx/ /home/private_html/usery/
Has anyone a solution to copy the directory "just as it is" into other place?
On FreeBSD, cp doesn't have an -r option. It does have -R, which should do what you want:
-R If source_file designates a directory, cp copies the directory and
the entire subtree connected at that point. If the source_file
ends in a /, the contents of the directory are copied rather than
the directory itself. This option also causes symbolic links to be
copied, rather than indirected through, and for cp to create spe‐
cial files rather than copying them as normal files. Created
directories have the same mode as the corresponding source direc‐
tory, unmodified by the process' umask.
Roland is right about the -R flag. You could also use a pair of tar-processes, which would make your command a little bit more system-independent:
tar -C /home/private_html/userx/ -cpf - . | tar -C /home/private_html/usery/ -epf -