Using xattrs or Extended Attributes on Linux

Using xattrs or Extended Attributes on Linux Extended attributes, xattrs for short, are an extensible mechanism to store metadata along files. In other words, they describe some additional properties of the file. Normally this information is limited, like ownership and dates. With xattrs more information can be stored about the file. Support for xattrs Not all file systems have support for xattrs, but nowadays the most common ones support it (EXT4, Btrfs, ReiserFS, JFS and ZFS). To determine if your […]

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Plus sign in ls output

Plus sign in ls output Every wondered what the plus (+) sign is when showing a directory listing? It is part of a POSIX standard to support access control lists (ACL) on files. Normal files on a file system will have only 10 characters displayed, with the last 9 used for file permissions. However when file access control lists are used, an 11th character shows up. This plus sign indicates the usage of a file ACL. root@earth:~/facls# ls -l total […]

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Using File ACLs on Linux for Additional Security

Using File ACLs on Linux for Additional Security File ACLs can increase security due to the more granular permission structure. Still the use of ACLs is often not known to system administrators, resulting in directories and files having inappropriate file permissions. When to use Example: a directory could be configured with very tight permissions, including a proper owner and group. Normally the “Other” (everyone) group would have to be used to open up the file for people outside the owner […]

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