CSC209H Worksheet: File Permissions
1. Consider the following listing of files as produced by ls -lF:
-rwx—— 1 reid instrs 418 Jan 16 09:23 day.txt*
-rw——- 1 reid instrs 13473 Jan 16 09:23 e1.pdf
drwxr-xr-x 2 reid instrs 4096 Jan 16 09:23 emptydir/
-rw-rw-rw- 1 reid instrs 835 Jan 16 09:23 student_list.txt
-rwxr-xr-x 1 reid instrs 9742 Jan 16 09:23 syscalls*
-rw-r–r– 1 reid instrs 197 Jan 16 09:23 syscalls.c
drwxr-xr-x 2 reid instrs 4096 Jan 16 09:25 test/
(a) Which regular files can be read by everyone?
(b) Circle the names of directories.
(c) Circle the size of the smallest regular file.
(d) Underline the names of the executable files.
(e) Give the command to remove read permission for others (not in the group) from all the files (including the directories) without changing any other permissions.
(f) Suppose you have a new file new_file and you don¡¯t know the permission. What is the command to set the file to be readable and writeable by the owner, readable by the group and not accessible at all to anyone else?
(g) Show the changes directly on the listing that would result from running the command
chmod 751 student_list.txt