However, when you recursively copy a directory tree containing symbolic links, they will be copied as symbolic links: $ cp -R another_dir/ copy_dir When you run cp on a symbolic link to a file, the contents of the original will be copied: $ cp another_dir/file filecopy When you use rm or mv on a symbolic link, only the link will be affected, not the original item. Also when the original file or directory gets deleted, a ‘dangling’ symbolic link will remain. Note: you can create a symbolic link that points to non-exiting path. to ‘go up a level’ out of the another_dir directory and then back into directory. Since you have to give the path to the target relative to the where the link is created you have to add the.
Will create a link named file pointing to. When the second argument is a directory itself, a link named the same as the file it refers to will be created: $ mkdir another_dir The correct command would have been: $ ln -s file directory/link_to_file The reference you pass when creating the symbolic link has to be relative to the where the symbolic link is created. When you try to read from the symbolic link pointing to nowhere, you will get an error: $ cat directory/link_to_fileĬat: directory/link_to_file: No such file or directory So if you wrote: $ ln -s directory/file directory/link_to_fileĪ symbolic link named link_to_file will be created in directory but it will point to directory/directory/file instead of the file next to it.
When this path is relative it will be resolved relative to the location of the symbolic link. The first argument is not really the path to a file or directory, but the path the symbolic link points to. When you want the symbolic link to have a different name, you can give that as a second argument: $ ln -s directory/file second_link
MAC SYMBOLIC LINKER SERIES
This series of commands will create a directory, and en empty file in directory and then a link to that file in the current working directory. To create a symbolic link use the ln -s command. The above link for /etc points to the relative path private/etc so to the sub-directory etc in the directory private in the same location as the symbolic link itself. Relative paths are resolved relative to the link itself, not the current working directory. However, most of the time they are relative, since you do not want them pointing to different files, depending on which volumes the system is booted from. Symbolic links can be relative or absolute. Note: the wc command counts words, lines and bytes in a file. When you read the file /usr/share/dict/words the read command will be redirected to /usr/share/dict/web2: $ cat /usr/share/dict/words | wc Symbolic links can be used as a means to ‘switch’ between files without having to change around filenames and configuration files. ls /tmp and ls /private/tmp will show you both the contents of the original /private/tmp.Īn example for a symbolic link to a file is the file /usr/share/dict/words (a list of english words, which can be surprisingly useful to have around) which points to a file web2 in the same directory. Most operations such as reading or changing are directed to the original, rather than the symbolic link. Lrwxr-xr-x 1 root wheel 11 Nov 17 07:50:53 2016 /etc -> private/etcĪ symbolic link contains a path pointing to the original file or directory. This is not used in macOS anymore, but the directory structure remains.Īside from the long ls you can use the readlink command to determine where a symbolic links points to: $ readlink /etc This setup could allow the /private folder to be mounted from another disk or file share separate from the rest of the system. Note: The reason for this is historical and goes back to NeXTStep. etc, /tmp and /var are standard directories for certain kinds of files in Unix systems, but in this case these directories are actually located in /private. Symbolic links are redirections to other files or directories. Symbolic links are identified by the first character l on a long ls. When you get a detailed list of the file system root / you will see a few interesting entries: (output abbreviated) $ ls -l 1 root wheel etc -> 1 root wheel tmp -> 1 root wheel var -> private/var
If you like this series and want to learn Terminal and the shell on macOS in more detail, get my book “ macOS Terminal and Shell“ Symbolic Links
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