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chmod unable to change permissions


I'm facing an annoying problem. It's been pretty frustrating. I am using a computer at my school to work on the Coursera Startup class. I am trying to connect to an Amazon EC2 instance. I downloaded the key pair. I check permissions.

mac5-library:startup roh21$ ls -l
total 6
-rw-rw-rw-@ 1 roh21  108  1692 Jun 22 16:45 startup-class-key.pem

So, it's not secure. So I need to change the permissions. I try:

mac5-library:startup roh21$ chmod 400 startup-class-key.pem
mac5-library:startup roh21$ ls -l
total 6
-r--r--r--@ 1 roh21  108  1692 Jun 22 16:45 startup-class-key.pem

Still has read permissions to everyone. Just to demonstrate what happens I do this:

mac5-library:startup roh21$ chmod 600 startup-class-key.pem
mac5-library:startup roh21$ ls -l
total 6
-rw-rw-rw-@ 1 roh21  108  1692 Jun 22 16:45 startup-class-key.pem

Is it impossible to change permissions to the user without root permission? I'd be grateful for any kind of help.


Solution

  • I copied the file to my ~/.ssh folder and then changed the permissions with chmod. That did it.

    Just to provide more information, the permissions for the ssh folder,

    drwx------    8 roh21  108      272 Jun 26 17:26 .ssh
    

    And the permissions to the folder I used initially

    drwxrwxrwx    2 roh21  108     2048 Jun 23 06:32 startup
    

    I curious as to why I could not change the permissions to the startup folder even after multiple attempts with the chmod -R option.

    Also, note that I was using Mac OS X in my school's library.