Logging out a remote SSH session through BASH command line prompt (or another SSH login session)

#To list all login sessions

$ who
user1    pts/0        2011-02-11 10:44 (abc.xyz.com)
user2    pts/1        2011-02-13 14:41 (def.xyz.com)
user1    pts/7        2011-02-11 10:44 (abc.xyz.com)
user1    pts/8        2011-02-11 10:44 (abc.xyz.com)

#To kill a login session pts/7 of user1
#root can kill anyone, user1 can kill user1 sessions

$ pkill -9 -t pts/7