Cfrtjryk

I want to add the socket=/tmp/mysql.sock to my.cnf file:
My steps:

1)

vi /etc/my.cnf

2）add this line in the my.cnf:

socket=/tmp/mysql.sock

3) but when I use :wq to quit:

I get this issue:

"/private/etc/my.cnf" E212: Can't open file for writing

Then I press enter it will go back to the my.cnf's content.

Additional -1

$ id 

aircraftdeMacBook-Pro:~ ldl$ id
uid=501(ldl) gid=20(staff) groups=20(staff),701(com.apple.sharepoint.group.1),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),33(_appstore),100(_lpoperator),204(_developer),395(com.apple.access_ftp),398(com.apple.access_screensharing),399(com.apple.access_ssh),702(com.apple.sharepoint.group.2)

Additional -2

$ ls -l /private/etc/my.cnf

ls: /private/etc/my.cnf: No such file or directory

Additional -3

In my mysql/support-files

You obviously don't have write access to mentioned file. To check it do:

ls -l /private/etc/my.cnf

To get know which user you are using use id command. You should either be an owner of the file or belong to the group that has write access (w letter in ls output) to this file.

Of course, you should be able to escalate your privileges to write this file. Use sudo or log in as a root.

Edit1:

Och, so you are using OSX :)
According to MySQL settings on OSX you need to create /etc/my.cnf file. You will have to use sudo to do that. So sudo vi /etc/my.cnf.
Note, that if this file is not present, then it would be wise to copy example configuration file as mentioned in above link and then edit it:

sudo cp /usr/local/mysql/support-files/my-huge.cnf /etc/my.cnf

sudo vi /etc/my.cnf

Sudo will ask for your administrator password (at least according to online help). This account needs to have password set.

Edit2:

File my-default.cnf looks good. Copy it to /etc/my.cnf and start editing.

sudo cp my-default.cnf /etc/my.cnf