Jan Kończak

1	whoami
2	groups
	id
3	id
	getent passwd your_username # uid is the third, and gid the fourth field
4	w -n
5	last -wn 10 # displays 10 last logons
6	last root
7	last --present '2023-03-03 13:30'
8	write username message Ctrl+d
9	su exit # lub Ctrl+d su user5 exit
10	ls -ld ~ ~/.ssh ~/.bash_history /etc/passwd /etc/shadow /tmp /usr/bin/passwd /usr/bin/write
	stat ~ ~/.ssh ~/.bash_history /etc/passwd /etc/shadow /tmp /usr/bin/passwd /usr/bin/write
	# the exercise shows examples of real-world permission usage; ponder why such permissions are set
11	ls -l /var/run /dev/sda /dev/nvme0n1 /dev/null /run/initctl /run/rpcbind.sock
	stat /var/run /dev/sda /dev/nvme0n1 /dev/null /run/initctl /run/rpcbind.sock
	# the exercise shows the possible file types (apart from an ordinary file and a directory)
12	fortune > file1 chmod go-r file1 su user2 cat file1 exit su user3 cat file1 exit
	fortune > file1 chmod go-r file1 su user2 -c "cat file1" su user3 -c "cat file1"
13	fortune > file2 chmod 640 file2 # verify as above
14	fortune > file3 chmod o-r file3 # alternatively: chmod u=rw,g=r,o= file3
15	chgrp left file3
16	fortune > file4 chmod 604 file4 # verify as in 31
17	mkdir dir1 fortune > dir1/a chmod -x dir1 ls dir1 cd dir1 cat dir1/a
18	chmod u=rwx,go=rx dir1 su user2 cat dir1/a ls dir1 exit chmod go-r dir1 # repeat cat and ls as user2
19	mkdir dir2 cd dir2 touch a b chmod go-r b su user2 rm a rm b exit
20	cd ~/dir2 su user2 mkdir d1 d2 touch d2/f exit rm -r d1 rm -r d2
21	cd ~/dir2 mv d2 foo mv foo ~ cd .. mkdir dir3 mv dir2 dir3
22	mkdir dir4 fortune > file5 fortune > dir4/f chmod -R 0 dir4 file5 su cat file5 cd dir4 cat f exit
23	su chown user2 file1 chown :www-data file2 exit
24	stat /var/log/wtmp # take notice of the last access date which might precede last modify date
25	touch ~
26	touch -d '13:30 PDT Saturday month ago' file