Si olvidaste la contraseña (password) del root, no te preocupes es posible restablecerla. este método es valido para la mayoría de sistemas operativos linux, tales como centos, debian, ubuntu, opensuse, etc…
Sigues los pasos siguientes:
Reinicia el sistema y cuando aparezca el menú de arranque GRUB2, pulsa la tecla «e«.
# push "e" key CentOS Linux (3.10.0-327.4.4.el7.x86_64) 7 (Core) with debugging CentOS Linux (3.10.0-327.4.4.el7.x86_64) 7 (Core) CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core) with debugging CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core) CentOS Linux 7 (Core), with Linux 3.10.0-229.el7.x86_64 CentOS Linux 7 (Core), with Linux 0-rescue-ffa496be96ad482cb94373394cec7 Use the ^ and v keys to change the selection. Press 'e' to edit the selected item, or 'c' for a command prompt. setparams 'CentOS Linux (3.10.0-327.4.4.el7.x86_64) 7 (Core)' 'fedora' load_video set gfxpayload=keep insmod gzio insmod part_msdos insmod xfs set root='hd0,msdos1' if [ x$feature_platform_search_hint = xy ]; then search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1' c4df086e-3699-4e02-b7cf-b47e614f6920 else search --no-floppy --fs-uuid --set=root c4df086e-3699-4e02-b7cf-b47e614f6920 fi # add "rw init=/bin/bash" to the end of line # remove "rhgb", "quiet", "LANG=***" all if there are in this line linux16 /vmlinuz-3.10.0-327.4.4.el7.x86_64 root=/dev/mapper/centos-root \ ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap console=ttyS0,115200n8 systemd.debug rw init=/bin/bash initrd16 /initramfs-3.10.0-327.4.4.el7.x86_64.img Press Ctrl-x to start, Ctrl-c for a command prompt or Escape to discard edits and return to the menu. Pressing Tab lists possible completions. # after inputting above, push "Ctrl-x" key to proceed ..... ..... [ OK ] Stopped udev Coldplug all Devices. Stopping udev Coldplug all Devices... [ OK ] Started Plymouth switch root service. [ 6.814528] systemd-journald[95]: Received SIGTERM from PID 1 (systemd). bash-4.2# # after initramfs switch_root prompt is displayed, do like follows # set SELinux relabeling on next boot if you enabling SELinux bash-4.2# touch /.autorelabel # set password bash-4.2# passwd Changing password for user root. New password: Retype new password: passwd: all authentication tokens updated successfully. # restart System and complete to reset bash-4.2# exec /sbin/init
Como ves, es un proceso rápido y sencillo.