Chan Parker and her daughter Kim are jazz lovers by night, and lovers of RHEL by day. Chan's husband Bird, a genius-level jazz alto saxophonist, has just read Jim Whitehurt's "The Open Organization" and he is quite intrigued. He asks him wife to give him a highg-level over of permissions on RHEL using chmod and setfacl/getfacl.  "Please giver me example commands", says Bird. What is Chan going to tell Bird?

Chan takes a moment to gather her thoughts and begins explaining to Bird about permissions on RHEL using chmod and setfacl/getfacl.

"Sure, Bird! On RHEL, we use the 'chmod' command to manage file permissions at a basic level. It allows us to modify the permissions for the owner, group, and others. Here are a few example commands using chmod:

  1. To give read, write, and execute permissions to the owner of a file: chmod u+rwx filename

  2. To remove write permissions for the group from a file: chmod g-w filename

  3. To add execute permissions for others to a directory: chmod o+x directoryname

These commands modify the permissions using the symbolic notation, where 'u' stands for the user/owner, 'g' for the group, and 'o' for others. '+' adds permissions, '-' removes permissions, and 'r' stands for read, 'w' for write, and 'x' for execute."

Chan continues, "However, if we need more advanced access control capabilities, we can use the 'setfacl' and 'getfacl' commands in addition to chmod. These commands enable us to manage Access Control Lists (ACLs) to provide more granular control over file and directory permissions. Here are a couple of examples:

  1. To grant read and write access to a specific user on a file: setfacl -m u:username:rw filename

  2. To display the ACLs for a file or directory: getfacl filename

The 'setfacl' command is used to modify ACLs by adding or modifying specific entries for users or groups, while 'getfacl' is used to retrieve and display the existing ACLs."

Chan concludes, "Remember, Bird, managing file permissions using chmod and ACLs with setfacl/getfacl provides us with the flexibility to control access at a more detailed level on our RHEL systems."

Bird nods, intrigued by the possibilities, and thanks Chan for the high-level overview of permissions on RHEL.

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