readlink Command in Linux
The readlink command in Linux is used to display the value of a symbolic link or canonicalize a path. Symbolic links, also known as symlinks or soft links, are special types of files that point to another file or directory.
The readlink command is particularly useful for resolving the target of a symbolic link or obtaining the absolute path of a file or directory.
Table of Contents
Here is a comprehensive guide to the options available with the readlink command â
- Understanding readlink Command
- Syntax of readlink Command
- readlink Command Options
- How to Use readlink Command in Linux?
Understanding readlink Command
When you run readlink followed by the name of a symbolic link, it prints the path to which the symbolic link points. This command is particularly useful for understanding the structure of symbolic links in your file system, especially when dealing with complex directory structures or troubleshooting issues related to broken links.
Additionally, readlink can be combined with various options, such as -f to canonicalize the path by following every symlink in every component of the given name recursively.
Syntax of readlink Command
The basic syntax of the readlink command is as follows:
readlink [options] filename
filename − The name of the symbolic link or file whose path you want to resolve.
readlink Command Options
Here are some common options used with the readlink command:
- -f, --canonicalize − Canonicalize by following every symlink in every component of the given name recursively.
- -e, --canonicalize-existing − Canonicalize by following every symlink in every component of the given name recursively, all components must exist.
- -m, --canonicalize-missing − Canonicalize by following every symlink in every component of the given name recursively, but a missing component is not an error.
- -n, --no-newline − Do not output the trailing newline.
- -q, --quiet, -s, --silent − Suppress most error messages.
- -v, --verbose − Print information about what is being done.
- -z, --zero − End each output line with NUL, not newline.
How to Use readlink Command in Linux?
The readlink command in Linux is used to display the target of a symbolic link. When using the readlink command, it is important to be aware of potential security risks. Since symbolic links can point to any file or directory, they could potentially be used to access sensitive information or perform unauthorized actions. It is important to ensure that the symbolic links you are working with come from trusted sources.
Displaying the Target of a Symbolic Link
To display the target of a symbolic link, you can use the following command:
readlink symlink
For example, if you have a symbolic link named mylink that points to a file named myfile, you would use:
readlink mylink
This command will display the target of the mylink symbolic link, which is myfile.
Canonicalizing a Path
To obtain the absolute path of a file or directory, you can use the -f option:
readlink -f myfile
For example, to obtain the absolute path of a file named myfile, you would use:
readlink -f myfile
This command will display the absolute path of the myfile file.
Canonicalizing a Path with Existing Components
To obtain the absolute path of a file or directory, ensuring that all components exist, you can use the -e option:
readlink -e path
For example, to obtain the absolute path of a file named myfile, ensuring that all components exist, you would use:
readlink -e myfile
This command will display the absolute path of the myfile file, ensuring that all components exist.
Canonicalizing a Path with Missing Components
To obtain the absolute path of a file or directory, allowing for missing components, you can use the -m option:
readlink -m path
For example, to obtain the absolute path of a file named myfile, allowing for missing components, you would use:
readlink -m myfile
This command will display the absolute path of the myfile file, allowing for missing components.
Displaying the Target of a Symbolic Link without a Trailing Newline
To display the target of a symbolic link without a trailing newline, you can use the -n option:
readlink -n symlink
For example, if you have a symbolic link named mylink that points to a file named myfile, you would use:
readlink -n mylink
This command will display the target of the mylink symbolic link without a trailing newline.
Suppressing Error Messages
To suppress most error messages, you can use the -q or -s option:
readlink -q symlink
For example, if you have a symbolic link named mylink that points to a file named myfile, you would use:
readlink -q mylink
This command will display the target of the mylink symbolic link, suppressing most error messages.
Displaying Information Verbosely
To display information about what is being done, you can use the -v option:
readlink -v symlink
For example, if you have a symbolic link named mylink that points to a file named myfile, you would use:
readlink -v mylink
This command will display the target of the mylink symbolic link and print information about what is being done.
Ending Each Output Line with NUL
To end each output line with NUL instead of a newline, you can use the -z option:
readlink -z symlink
For example, if you have a symbolic link named mylink that points to a file named myfile, you would use:
readlink -z mylink
This command will display the target of the mylink symbolic link, ending each output line with NUL instead of a newline.
Symbolic Links Overview
Symbolic links, also known as symlinks or soft links, are special types of files that point to another file or directory. They are similar to shortcuts in Windows. Symbolic links can be created using the ln -s command. For example:
ln -s target symlink
This command creates a symbolic link named symlink that points to the target file or directory.
Error Handling
When using the readlink command, you may encounter various errors. Here are some common ones and how to handle them:
No such file or directory: This error occurs if the specified symbolic link or file does not exist. Double-check the file path and ensure that the file exists.
Conclusion
The readlink command is a useful tool for resolving the target of symbolic links and obtaining the absolute path of files and directories. By understanding the syntax, options, and common use cases of the readlink command, you can effectively use it to manage and manipulate file paths in Linux.
Whether you are a developer, system administrator, or security researcher, the readlink command provides valuable insights into the structure and organization of file systems.