LFCS Certification Filesystem Permissions and ACLs 3

Question 1

A user's umask is 027. What permissions will a newly created regular file have?

Accepted Answer

640

Answer

Files start at 666 max; 666 minus umask 027 gives 640 (rw-r-----) for regular files.

Question 2

What does 'setfacl -d -m g:developers:rwx projectdir' accomplish?

Accepted Answer

Sets a default ACL so new files in projectdir inherit rwx for the developers group

Answer

The -d flag sets a default ACL entry that is automatically inherited by new files and subdirectories created inside the directory.

Question 3

Which ls option shows a '+' indicator next to files that have extended ACLs?

Accepted Answer

ls -l

Answer

ls -l displays a '+' at the end of the permission string for any file or directory that has an extended ACL beyond the standard POSIX permissions.

Question 4

A script has permissions '-rwsr-xr-x' and is owned by root. What happens when a normal user runs it?

Accepted Answer

It runs with root privileges due to the setuid bit

Answer

The setuid bit (s in the owner execute position) causes the process to run with the file owner's (root's) effective UID.

Question 5

How do you copy a file's ACL from 'source.txt' to 'dest.txt'?

Accepted Answer

getfacl source.txt | setfacl --set-file=- dest.txt

Answer

Piping getfacl output into setfacl --set-file=- is the standard way to copy ACL entries between files.

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