Join Kevin Skoglund for an in-depth discussion in this video Symbolic links, part of Unix for Mac OS X Users.
In this movie we are going to look at what's called symbolic links.…These are also called sym links for short.…So you'll often hear me just say sym link.…We create them the same way as we do the hard links. We just use ln, short for…link, but we use the -s option to indicate that it's a symbolic link.…So ln -s and then the file that we want to link or a path to the file that we…want to link, followed by the name of the link or a path with the name at the end, …just like we did for hard links.…We have our target followed by the name of the link.…
Where symbolic links are very different from hard links is that symbolic links…reference the path to the file.…That's what they keep track of, is the path to get to that file.…Not the file itself.…So hard links keep track of the file on the hard drive and point to that file;…instead symbolic links keep track of the fact, which directory is this file embedded in.…As a consequence that means that they break if the file is moved.…The file is no longer at that path, well, then when we try and do something with…
- Moving around the file system
- Creating and reading files
- Copying, moving, renaming, and deleting files and directories
- Creating hard links and symbolic links
- Understanding user identity, file ownership, and sudo
- Setting file permissions with alpha and octal notation
- Changing the PATH variable
- Using the command history
- Directing input and output
- Configuring the Unix working environment
- Searching and replacing using grep and regular expressions
- Manipulating text with tr, sed, and cut
- Integrating with the Finder, Spotlight, and AppleScript
Skill Level Beginner
Q: The exercise files for the following movies appear to be broken:
Is there something wrong with them?
These exercises include one or more "dot files", whose file names start with a period. These files are normally hidden from view by the Finder. So that they would show up in the Finder, the period has been removed from the file names. Additionally, "_example" has been added at the end of the file name to make it clear that the file will not work as-is.
To make the dot files usable, either:
1) Open the file in a text editor to view its contents. Note that it may not be possible to double-click the file to open it because there is no file extension (such as .txt).
2) Resave the file under a new name (usually by choosing File > Save As), adding a "." to the beginning of the file name and removing "_example" from the end.
1) Copy and rename the file from the Unix command line using the techniques discussed in this course. Rename the file by adding a "." to the start and removing "_example" from the end. Include the "-i" option to prevent overwriting an existing file unexpectedly.
Example: cp -i ~/Desktop/Exercise\ Files/Chapter_07/07_02_files/bashrc_example ~/.bashrc
1. Introduction to Unix
2. Filesystem Basics
3. Working with Files and Directories
4. Ownership and Permissions
5. Commands and Programs
6. Directing Input and Output
7. Configuring Your Working Environment
8. Unix Power Tools
9. Useful Mac-Only Commands and Techniques
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