147 lines
3.5 KiB
Org Mode
147 lines
3.5 KiB
Org Mode
#+options: toc:nil num:nil author:nil
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* Changing permissions for files and directories
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There are three types of permissions for files and directories in the system:
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| Permission | Files | Directories |
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|---------------+-----------------+-------------------|
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| Read ('r') | Read the file | List contents |
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| Write ('w') | Change the file | Create amd remove |
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| Execute ('x') | Execute files | Access the files |
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Permissions can be differente for different users:
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- Owner of the files
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- Group: other users in the file's group
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- Others
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** Creating a file and checking permissions
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Here we create a file with the sentence "this is a fancy file". The sentence is
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redirected to the name "fancyfile.org" and a new file is created!
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#+begin_src bash
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echo "this is a fancy file" > fancyfile.org
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#+end_src
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#+RESULTS:
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In the ouptut of ~ls~ command, there letters showing each permission for each user: owner, group, others, respectively.
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#+begin_src bash
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ls -la fancyfile.org
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#+end_src
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#+RESULTS:
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: -rw-r--r-- 1 user user 21 jul 18 06:06 fancyfile.org
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** Settings permissions for the file
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Setting permissions for the
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- User who owns the file = "u"
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- Other users in the group = "g"
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- Other users = o
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You may change the permissions for each user, using letters (r-w-x):
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#+begin_src bash
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chmod u=r, g=rw, o=r fancyfile.org
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#+end_src
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#+RESULTS:
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Then it changed!
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#+begin_src bash
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ls -la fancyfile.org
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#+end_src
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#+RESULTS:
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: -r--rw-r-- 1 user user 21 jul 18 06:06 fancyfile.org
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** Changing permission for directories
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Let's say I (unintentionally) changed the permissions for a directory that
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contains multiple subdirectories. Let's call that directory "buds"
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I can't access the files without being `root`. This is the outuput in the
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command line When a list the directory using `ls -la`.
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#+begin_example bash
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drw-r--r-- 81 user user 4096 dec 26 06:21 buds
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#+end_example
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When I go to my git repository and check the change I can see this output for
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every file within the directory:
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#+begin_example bash
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diff --git a/doc/index.rst b/doc/index.rst
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old mode 100644
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new mode 100755
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#+end_example
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Thus, the directory has the following permissions
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- For the owner = read (4) and write (2)
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- For the group = read (4)
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- For others = read (4)
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Using ~chmod~ 744 will change the permissions for:
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* The owner (4 = read; 2 = write; 1 = execute)
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* The group (4 = read) and
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* Others (4 = read)
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Applying the same logic to a file:
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#+begin_src bash
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chmod 744 NameOfFileHere
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#+end_src
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Use ~-R~ if you want to apply recursive ~chmod~
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#+begin_src bash
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chmod -R 755 NameOfFileHere
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#+end_src
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*** The output now is:
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#+begin_example bash
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drwxr-xr-x 81 user user 4096 dec 26 06:21 buds
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#+end_example
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Remember how it was before
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#+begin_example bash
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drw-r--r-- 81 user user 4096 dec 26 06:21 buds_before
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#+end_example
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** Changing owner
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But I still can open the files. That is because need to change the owner.
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To change the owner of files the command ~chown~ may be used
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#+begin_example bash
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chown NameOfownerHere buds # Try this and check the result
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#+end_example
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Include the owner then ~:~ and then the name of the group to change ownership for each one of those users
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#+begin_example bash
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chown user:usergroup buds # Then try this and check the result
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#+end_example
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ps: should use`sudo` to run this command, so be careful and make a scratch directory
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to run tests.
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** References
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- Check the manual: info -> Coreutils -> File permissions. In bash: ~info coreutils~
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Coreutils are standard programs for text and file manipulation
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