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| -rw-r--r-- | README.md | 35 | ||||
| -rw-r--r-- | exercises/chapter-8.14 | 15 |
2 files changed, 49 insertions, 1 deletions
@@ -297,7 +297,40 @@ $ cp /etc/passwd dir1 See `exercises/chapter-8.13`. -14. What umask command should be executed to set the permissions bit mask to 037? With this mask, what default access privileges are associated with any new file that you create on the system? Why? Where would you put this command so that every time you log on to the system this mask is effective? +14. What `umask` command should be executed to set the permissions bit mask to `037`? With this mask, what default access privileges are associated with any new file that you create on the system? Why? Where would you put this command so that every time you log on to the system this mask is effective? + +The `umask` indicates which permission bits to turn off. ie. `777 - mask`. + +To change the default umask to `037`. + +```bash +$ touch before +$ umask 037 +$ umask after +$ ls -alh before after +-rw-r-----. 1 root root 0 May 25 19:03 after +-rw-r--r--. 1 root root 0 May 25 19:03 before +``` + +The default access privileges are: + +```text +777 - 037 = 740 + +rwx|r--|--- +``` + +User: Read, write, execute. +Group: Read +Everyone: no access + +The `umask` can be placed in any startup scripts such as: + +* $HOME/.profile (System V UNIX) +* $HOME/.login (BSD UNIX) +* $HOME/.bash\_profile + +See `exercises/chapter-8.14`. 15. Give a command line for setting the default access mode so that you have read, write, and execute privileges, your group has read and execute permissions, and all others have no permission for a newly created executable file or directory. How would you test it to be sure that it works correctly? diff --git a/exercises/chapter-8.14 b/exercises/chapter-8.14 new file mode 100644 index 0000000..172cfdd --- /dev/null +++ b/exercises/chapter-8.14 @@ -0,0 +1,15 @@ +Script started on 2019-05-25 13:08:45-06:00 [TERM="screen-256color" TTY="/dev/pts/7" COLUMNS="238" LINES="13"] +bash-5.0$ docker run -it fedora /bin/bash
+]0;@d8fb6f3d47d3:/[root@d8fb6f3d47d3 /]#
[K[root@d8fb6f3d47d3 /]# cd
+]0;@d8fb6f3d47d3:~[root@d8fb6f3d47d3 ~]# touch before
+]0;@d8fb6f3d47d3:~[root@d8fb6f3d47d3 ~]# umask 037
+]0;@d8fb6f3d47d3:~[root@d8fb6f3d47d3 ~]# touch after
+]0;@d8fb6f3d47d3:~[root@d8fb6f3d47d3 ~]# ls -alh before after
+-rw-r-----. 1 root root 0 May 25 19:09 after
+-rw-r--r--. 1 root root 0 May 25 19:08 before
+]0;@d8fb6f3d47d3:~[root@d8fb6f3d47d3 ~]# exit
+exit
+bash-5.0$ exit
+exit
+ +Script done on 2019-05-25 13:09:08-06:00 [COMMAND_EXIT_CODE="0"] |