Some users are able to run commands as another user.
sudo
Usually the sudo command is used to execute a command using root privileges.
Only elevate your privileges to root when needed.
sudo cat /etc/passwd
# Runs the cat command as root
sudo -u user2 cat /home/user2/test.txt
# Runs the cat command as "user2" user
su
su - change user
su user2
su --help
Usage:
su [options] [-] [<user> [<argument>...]]
Change the effective user ID and group ID to that of <user>.
A mere - implies -l. If <user> is not given, root is assumed.
Options:
-m, -p, --preserve-environment do not reset environment variables
-w, --whitelist-environment <list> don't reset specified variables
-g, --group <group> specify the primary group
-G, --supp-group <group> specify a supplemental group
-, -l, --login make the shell a login shell
-c, --command <command> pass a single command to the shell with -c
--session-command <command> pass a single command to the shell with -c
and do not create a new session
-f, --fast pass -f to the shell (for csh or tcsh)
-s, --shell <shell> run <shell> if /etc/shells allows it
-P, --pty create a new pseudo-terminal
-h, --help display this help
-V, --version display version
passwd
passwd - change user password
passwd
# Change current user's password
sudo passwd user2
# Change another user's password using an elevated user
