What is the best way to configure file system permissions in Linux?

1 Why file system permissions matter

File system permissions are essential for security, privacy, and functionality of a Linux system. They prevent unauthorized users from accessing or altering sensitive data, such as passwords, configuration files, or personal information. They also ensure that only the intended users or programs can run executable files, such as scripts, binaries, or applications. File system permissions can also affect the performance and compatibility of a Linux system, as some files or directories may require specific permissions to function properly.

5 How to use umask to set default file system permissions

The umask command is used to set the default file system permissions for newly created files and directories in Linux. It takes one argument: a mask. The mask is a four-digit number that represents the permissions to be subtracted from the default permissions. The default permissions are 666 for files and 777 for directories, which means read and write permissions for all entities. The mask can be expressed in symbolic or numeric mode, similar to chmod. For example, umask u=rwx,g=rx,o= means to set the default permissions to 740 for files and 750 for directories, which means read, write, and execute permissions for the owner, read and execute permissions for the group, and no permissions for others.

6 Some common pitfalls and best practices

When configuring file system permissions in Linux, it is important to be mindful of common pitfalls and adhere to best practices. For instance, granting too many permissions to others can compromise the security and privacy of the system, while giving too few permissions to the owner or group can prevent functionality and compatibility. Additionally, changing the permissions of system files or directories can lead to errors or malfunctions. To ensure a secure system, it is best to use the principle of least privilege, meaning granting only the minimum permissions necessary for each entity to perform its tasks. Additionally, groups can be used to manage permissions for multiple users who share a common purpose or affiliation, and symbolic links can refer to files or directories that require different permissions than their original locations.