What could be the reasons if another user uses the same terminal, has disk space and RAM, but cannot create folders?

The reasons why a user cannot create folders despite having free space and memory may be related to access rights. For example:

• Lack of write permissions in the current directory (insufficient filesystem permissions).
• Restrictions at the ACL or SELinux/AppArmor level blocking the creation of new directories.
• Reached the limit on the number of files or folders in the directory (e.g., inode limit).
• The filesystem is mounted in read-only mode.

You can check using commands like ls -ld <path>, mount, and df -i for inodes, as well as by reviewing permissions and security policies.

Lack of write permissions in the current directory or in the intended location for creating a folder.

# Check access rights to the current directory
ls -ld .

Lack of execute permission (execute) on the parent directory.

# Check access rights to the parent directory
ls -ld ..

Restrictions imposed by ACL (Access Control Lists).

# Check for ACL presence
getfacl .

The filesystem is mounted in read-only mode.

# Check mount mode
mount | grep /path/to/directory

Corruption of the filesystem or inode issues.

# To check the filesystem, a reboot or unmounting daemon may be required
# fsck /dev/sdX

Disk space quota restrictions for the user or group.

# Check quotas
quota -v

Immutable attribute (immutable) present on the directory.

# Check attributes
lsattr .
# Remove immutable attribute (requires superuser)
# chattr -i .

Working directory is on a network resource with write restrictions.

Presence of special security modules (e.g., SELinux or AppArmor) with policies that prohibit creating files/directories.

# Check SELinux status
sestatus
# Check SELinux mode
getenforce

System or process failures blocking access to the filesystem.