If you need to leave a long job, such as a program that will run for longer than 5 hrs, or a jupyter notebook you might have noticed errors such as "Broken Pipe" or about your access to AFS being expired.
rm: cannot remove '/afs/inf.ed.ac.uk/user/s20/UUN/.last_login': Permission denied
-bash: /afs/inf.ed.ac.uk/user/s20/UUN/.last_login: Permission denied
-bash: cd: /afs/inf.ed.ac.uk/user/s20/UUN: Permission denied
-bash: /afs/inf.ed.ac.uk/user/s20/UUN/.bash_profile: Permission denied