1. File System Security ls -l

2. First Columm d = directory l = symbolic link b = block special file c = character special file p = fifo (or named pipe) special file - = ordinary file s = named socket special file

3. rwx --- --- – user “owner” permissions: – if you created it, you own it --- rwx --- – group “owner” permissions: – you and other people in the owner’s group --- --- rwx – other “world” permissions: – everyone else Second Column

4. Three types of file access: Read – List the contents of a file Write – Update the contents of the file Execute – If the file is a program, run it Three types of directory access: Read – List the files in the directory Write – Rename or delete files in the directory, or copy files to the directory Execute – cd to the directory

5. chmod chmod u (user) chmod g (group) chmod a (all) – chmod u+w./quarters = add write permission to user – chmod g+rwx./quarters = add all permssions to all – chmod a-wx./quarters = remove write and execute for all

6. chmod ReadWriteExecuteOctal OutcomeOutcome 4217rwx 42-6rw- 4-15r-x 4--4r-- -213-wx -2-2-w- --11--x chmod 744./quarters chmod 774./quarters chmod 544./quarters

7. umask Change the system-wide default permission Default permissions for all files created in the future until umask is changed umask 077

8. chown chown = change file ownership chown hoffmann./quarters

9. chgrp chgrp = change group owner chgrp thegame./quarters

10. newgrp switching groups newgrp thegame