Symbolic links create linux

A symbolic link, also known as a symlink or a soft link, is a special kind of file (entry) that points to the actual file or directory on a disk (like a shortcut in Windows).

Symbolic links are used all the time to link libraries and often used to link files and folders on mounted NFS (Network File System) shares.

The ln command is a standard Linux utility for creation links.

Cool Tip: Creating a symlink to a mounted NFS? Have you already thought about performance? Test the READ/WRITE speed to a remote share from the Linux command line! Read more →

Below you’ll find how to create a symbolic link to a file and a folder from the Linux command line.

Easy to remember: Generally, the ln syntax is similar to the cp or mv syntax, e.g. .

Use the following syntax to create a symbolic link in Linux:

Nevertheless you should know, that according to the man page, by default, each destination (
) should not already exist.

If the path to the

  • exists and it is a file, you will get an error like “ln: failed to create symbolic link ‘
  • ’: File exists”.

    But if the path to the
    is an existent directory, link will be created inside that directory.

    Create a symbolic link to a file:

    To create a symbolic link to a directory you should use exactly the same syntax as for creating a symlink to a file.

    Cool Tip: Have added a new drive to /etc/fstab ? No need to reboot! Mount it with one command! Read more →

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    Learning Linux symbolic commands is a great way of improving your potential in the Linux terminal. In this tutorial, we’ll cover a few commands to learn symbolic links in a quick and easy way. Before we begin, let’s overview what are symbolic links.

    Symbolic Links are not only helpful in creating shortcuts and file management in operating systems like Linux. They also serve as a way to create various locations for primary user folders, for instance, Documents, Pictures, Downloads, and much more!

    Symbolic Links act like a string creating pathways for different files, folders, and directories in the computer system. They are capable of creating and storing multiple files in different places refer to one single file. Thus, increasing efficiency by locating all the specific documents in one command.

    These links are stored in the mainframe, so even if the original file is deleted, you’ll have a backup for most of the important files. Symbolic links help create invalid link pathways to store pieces of information as per the requirement of the user.

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    Due to the user-friendly features in Linux, even Microsoft is following it to create Symbolic Links. Symbolic links, also known as Soft links or Symlinks, are not unique to Linux but they are just like a Search option in Windows where one can search a specific file or directory in a disk by executing various commands.

    Let’s look at how you can create file and folder links in Linux:

    Generally, to create links use we use the ln command and the -s option to specify Symbolic links. This is the easiest way to ensure a flexible approach that allows experimenting with the language as much as possible. There is nothing hard in creating Symbolic links in Linux – you just need to follow one simple step.

    The ln command in Linux creates links between source files and directories.

    • -s – the command for Symbolic Links.
    • [target file] – name of the existing file for which you are creating the link
    • [Symbolic filename] – name of the symbolic link.

    Created links can be verified by directory listing using detailed list command:

    However, if you do not specify the [Symbolic filename], the command will automatically create a new link in the existing directory.

    Creating symbolic links for folders is not difficult either. The command used to create the folder symbolic link is:

    For example, to link the /user/local/downloads/logo directory to /devisers folder, use the following command:

    Once a Symbolic link is created and attached to the folder /devisers, it will lead to /user/local/downloads/logo. When the user changes directory – cd – to /devisers, the system will automatically change to the specific file and write it in the command directory.

    Symbolic link options are called command line switches. Here are the most common ones and their descriptions:

    Command Switch Description
    –backup[=CONTROL] backup each existing destination file
    -d, -F, –directory superuser is allowed to attempt hard link
    -f, –force existing destination file is removed
    -I, –interactive prompt before removing destination files
    -L, –logical deference targets that are symbolic links
    -n, –non-dereference symbolic links to directory are treated as files
    -P, –physical make hard links directly to symbolic links
    -r, –relative create symbolic links relative to link location
    -s, –symbol make symbolic links instead of hard links
    -S, –suffix=SUFFIX override usual backup suffix
    -v, –verbose print name of each linked file

    You can remove existing links attached to files or directories by the unlink or rm command. This is how you can do it with the unlink command:

    Removing symbolic link using the rm command is similar to the unlink command which is as under:

    Wrapping up

    Remember, if the source is no longer in the current location, then you should delete the symbolic files to avoid creating duplicates, which might slow down your work.

    Linux is a wonderful platform for creating an interactive and dynamic application, where you can experiment and innovate. A strong foundation is critical. Learn the basic of the language thoroughly to use it to its full potential. We hope this tutorial helped you improve your skills with another useful tool!

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    Edward is an expert communicator with years of experience in IT as a writer, marketer, and Linux enthusiast. IT is a core pillar of his life, personal and professional. Edward’s goal is to encourage millions to achieve an impactful online presence. He also really loves dogs, guitars, and everything related to space.

    Источник

    linux-notes.org

    Хотелось бы рассказать как можно создавать ссылки (симлинки) в ОС Unix/Linux. В своей теме «Создание ссылок (symlink) в Unix/Linux» я на готовом примере покажу как это делается. Существуют несколько видов ссылок, и я расскажу в чем разница между ними.

    Симлинк или мягкая ссылка представляет собой особый тип файла, который содержит ссылку на другой файл или каталог в виде абсолютного или относительного пути.

    Жёсткой ссылкой — это структурная составляющая файла которая описывает его элемент каталога.

    В этом подразделе, я расскажу какие бывают симлинки и в чем они отличаются.

    Мягкая ссылка (Soft link):

    1. Мягкие ссылки используют различные номера инод чем основные файлы.
    2. Мягкие ссылки становится полезными, если исходный файл был удален.
    3. Мягкие ссылки могут быть созданы из каталогов.
    4. Мягкая ссылка может быть создана на пересечении файловых систем.

    Для того чтобы создать симлинк в линукс используется следующая команда:

    И так, я создал симлинк linux-notes.org.conf на на тот же файл но который будет расположен в другой директории. После создания симлинка, необходимо сменить права на него:

    Для проверки номера иноды:

    Я создал симлинк на файл, так же, можно создавать симлинка на целую папку, для этого используйте:

    И так, я создал симлинк symlink-to-opt-dir на папку /opt/directory. После создания симлинка, необходимо сменить права на него:

    Вот и все, очень просто, и полезно.

    Для проверки номера иноды:

    Чтобы удалить, используйте:

    И аналогично для каталогов.

    Если вы удалите мягкую ссылку (/home/captain/linux-notes.org-softlink.txt), то сам файл данных будет по-прежнему находится там же (/home/captain/linux-notes.org.txt). Тем не менее, если вы удалите /home/captain/linux-notes.org.txt, то /home/captain/linux-notes.org-softlink.txt станет сломанной ссылкой и данные будут потеряны.

    Жесткие ссылки (Hard Links):

    1. Жесткие ссылки использует тот же номер иноды что и основные файлы.
    2. Нельзя создать жесткие ссылки на каталоги.
    3. Жесткие ссылки не могут быть созданы на пересечении файловых систем.
    4. Жесткие ссылки всегда относится к источнику, даже если они перемещаются или удаляется.

    Чтобы создать «жесткую ссылку», используйте:

    Проверяем номер иноды:

    Оба файла имеют одинаковые иноды (одинаковое количество индексных дескрипторов). Если нужно удалить «жесткую ссылку», то используйте команду:

    Если вы удалите жесткую ссылку, ваши данные будут там. Если вы удалите /home/captain/linux-notes.org.txt то файл будет по-прежнему доступен через жесткую ссылку

    Жесткие ссылки (Hardlink) vs Мягкие ссылки (Softlink) в UNIX/Linux

    • Как я говорил ранее, жесткие ссылки не могут быть созданы для директорий.
    • Жесткие ссылки не могут использоваться на пересечении границ файловых систем ( Нельзя создать сылку /tmp и примонтированную на /tmp ко 2-му HDD который смонтирован на/harddisk2).
    • Символические ссылки (мягкие ссылки) ссылаются на символичный путь с указанием абстрактного расположение другого файла.
    • Жесткие ссылки, ссылаются к определенному местоположению физических данных.

    На этом, моя тема «Создание ссылок (symlink) в Unix/Linux» завершена. Не сильно сложная тема, но очень полезная.

    Источник

    Symbolic links can be made to directories as well as to files on different filesystems or different partitions.

    • symbolic links (also known as “soft links” or “symlinks”): Refer to a symbolic path indicating the abstract location of another file.
    • hard links : Refer to the specific location of physical data.
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    Soft links are created with the ln command. For example, the following would create a soft link named link1 to a file named file1, both in the current directory
    $ ln -s file1 link1
    To verify new soft link run:
    $ ls -l file1 link1
    Sample outputs:

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    From the above outputs it is clear that a symbolic link named ‘link1’ contains the name of the file named ‘file1’ to which it is linked.

    How to use the ln command

    So the syntax is as follows to create a symbolic link in Unix or Linux, at the shell prompt:
    $ ln -s < source-filename >< symbolic-filename >

    For example create a softlink for /webroot/home/httpd/test.com/index.php as /home/vivek/index.php, enter the following command:
    $ ln -s /webroot/home/httpd/test.com/index.php /home/vivek/index.php
    $ ls -l
    Sample outputs:

    You can now edit the soft link named /home/vivek/index.php and /webroot/home/httpd/test.com/index.php will get updated:
    $ vi /home/vivek/index.php
    Your actual file /webroot/home/httpd/test.com/index.php remains on disk even if you deleted the soft link /home/vivek/index.php using the rm command:
    $ rm /home/vivek/index.php ## ##
    ## But original/actual file remains as it is ##
    $ ls -l /webroot/home/httpd/test.com/index.php

    The syntax remains same:
    $ ln -s
    For example, create a symbolic link from the /home/lighttpd/http/users/vivek/php/app/ directory to the /app/ directory you would run:
    $ ln -s /home/lighttpd/http/users/vivek/php/app/ /app/
    Now I can edit files using /app/
    $ cd /app/
    $ ls -l
    $ vi config.php

    Pass the -f to the ln command to overwrite links:
    ln -f -s /path/to/my-cool-file.txt link.txt

    Use the rm command to delete a file including symlinks:
    rm my-link-name
    unlink /app/
    rm /home/vivek/index.php

    Getting help about the ln command

    Type the following ln command:
    $ man ln
    $ ln —help

    ln command option Description
    —backup make a backup of each existing destination file
    -b like —backup but does not accept an argument
    -d allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser)
    -f remove existing destination files
    -i prompt whether to remove destinations
    -L dereference TARGETs that are symbolic links
    -n treat LINK_NAME as a normal file if it is a symbolic link to a directory
    -P make hard links directly to symbolic links
    -r create symbolic links relative to link location
    -s make symbolic links instead of hard links
    -S override the usual backup suffix
    -t specify the DIRECTORY in which to create the links
    -T treat LINK_NAME as a normal file always
    -v print name of each linked file
    —help display this help and exit
    —version output version information and exit

    Conclusion

    You learned how to create a symbolic link in Linux using the ln command by passing the -s option. See ln command man page here for more information.

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