What should you check if you're experiencing permission problems in Linux?

When troubleshooting permission problems in Linux, it’s crucial to consider a comprehensive approach, which is why examining all the suggested areas is important.

Checking filesystem quotas and umask settings is vital because quotas can limit the amount of disk space or number of files a user can create, which can lead to permission issues if a user exceeds those limits. The umask setting determines the default permissions for newly created files and directories; if it’s set incorrectly, it can also lead to unexpected permission problems that hinder access or modifications.

Reviewing kernel security module log files can provide insights into access denials caused by security modules such as SELinux or AppArmor, which enforce stricter access controls than traditional Linux permission settings. These logs can reveal if permissions are being denied due to mandatory access control policies.

Lastly, checking disk space and inode use is important because if the filesystem is full (meaning no free space is available) or if the user has exhausted their allocation of inodes (the data structures that store information about files), it can lead to system errors that mimic permission issues.

In summary, a thorough investigation across all these areas allows for identifying and resolving permission issues effectively, making this answer the most appropriate choice.