How to modify root permissions for non-root users under Linux

under Linux, there will be some configuration file parameter mismatch, root password forgotten and so on, causing the system to fail to start or enter the root of the distress situation, this article to Redhat Enterprise Linux Server 6.4 as an example of root identity change root         After the parameters of the permissions profile, root cannot log in, and then change the Linux rescue mode back to the configuration file, subtly modifying the root file's solution as a non-root identity. First, insert the Linux installation disk to restart the system, wait until the boot into the installation session, move the arrow keys up and down, select Rescue installed system; second, after entering the repair mode, the system will prompt for the language, keyboard type and method type, the system will be prompted to enter the line; To turn on the network, select No, no network access in the repair mode; third, then the Continue,rescue program will find out if there is a Linux system installed on the current hard disk, if found will be mounted to/mnt/sysimage, can read and write. After selecting OK, the system will go into the repair mode under the shell, and cd/mnt/sysimage can then change the password, or edit the corresponding file with vi/etc/security/limits.conf, in rescue mode, cannot delete The contents of the original file can only add new content, only one row at a time, you can add #, the previous modified content comments, and then add new content; Five, after the modification save, execute reboot, remove the disc, you can enter the previous system.