chacl

chacl [options] file...

Note: As chacl is deprecated and functionally equivalent to setfacl, its synopsis mirrors that of setfacl.

-m acl_entries
    Modify the ACL of files. This option is used to add or modify ACL entries.

-x acl_entries
    Remove specified ACL entries from files.

-b
    Remove all extended ACL entries. Only base ACL entries (owner, group, others) remain.

-k
    Remove the default ACL from directories.

-d acl_entries
    Set default ACL entries for directories. New files/directories created within will inherit these.

-R
    Recursively apply operations to directories and their contents.

--restore file
    Restore an ACL backup from a file, typically created by getfacl --omit-header.

--test
    Test mode: show what would be done, but do not make any changes.

--version
    Display the version information.

--help
    Display help message.

chacl is a command in Linux used to manipulate Access Control Lists (ACLs) on files and directories. ACLs provide a more granular permission system than the traditional Unix owner, group, and others permissions, allowing specific users or groups to be granted read, write, or execute permissions on a file, overriding the default permission model.

Historically, chacl was used for this purpose. However, on modern Linux systems, chacl is considered deprecated. It is typically provided for backward compatibility and acts as a symbolic link or a wrapper that is functionally equivalent to the setfacl(1) command. Therefore, while chacl might still exist on your system, the recommended and actively maintained tool for managing ACLs is setfacl. Users should migrate to using setfacl for all ACL manipulation tasks.

The primary caveat for chacl is its deprecation. It is no longer actively developed and maintained as a standalone tool. Modern Linux distributions provide setfacl as the preferred and more robust command for managing Access Control Lists. Relying on chacl might lead to unexpected behavior or lack of desired functionality on newer systems where it simply acts as a compatibility layer.

setfacl is the officially recommended command for managing ACLs on Linux systems. It is actively maintained, offers a richer set of features, and provides consistent behavior across distributions. Using setfacl ensures compatibility with current ACL standards and best practices, unlike chacl which is a legacy command.

Before using ACL commands, ensure that the filesystem is mounted with ACL support. This is typically done by default for common filesystems like ext4, xfs, and btrfs. You can check mount options using mount or cat /proc/mounts and looking for the 'acl' option.

The concept of Access Control Lists has been part of Unix-like systems for a long time, providing finer-grained control over file permissions than the traditional UID/GID/others model. chacl was one of the early commands designed to interact with these ACLs. As the Linux kernel's ACL implementation matured and standardized, the acl package emerged, introducing setfacl and getfacl as the primary utilities. Over time, setfacl became the more comprehensive and standardized tool. Consequently, chacl was marked as deprecated and largely superseded by setfacl, maintained primarily for backward compatibility for older scripts or muscle memory.

setfacl(1), getfacl(1), acl(5), chmod(1), chown(1)