问题
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.
回答1:
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.
回答2:
Looks like you've discovered that the Macintosh doesn't strictly agree with the UNIX permission bits.
Ultimately, there are ACL bits that MacOS sets and that the Macintosh Finder obeys.
To solve your problem quickly, in your Terminal command line, type in "open ." (or the path to your "startup" folder) and that will open up the folder in your Macintosh Finder.
Then do a "Get Info" on the file:
You can change your permissions here.
回答3:
it WORKS!
- When manually selected the file and from Get info modified the permission. But it failed to do so while trying
chmod -R 777 msg.html
回答4:
Probably not related to initial questions problem, but can be useful. (especially to Unix novices like myself)
Chmod will not work if you are not an owner of resources.
You should run chown first:
$ sudo chown -R $(whoami) .
and then
$ sudo chmod -R +rwX .
First command will change owner of everything in current folder to be logged in user, and second give him read write execute permissions. Just for example, you, probably, should not change ownership and permissions so boldly.
来源：https://stackoverflow.com/questions/17255340/chmod-unable-to-change-permissions