How to boot into emergency or multi-user mode from GRUB2

Solution Verified - Updated

Environment

  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 9
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 7

Issue

  • How to boot into the emergency target (formerly single user mode) or multi-user target (equivalent to runlevel 3 in RHEL6/RHEL5) in GRUB2?

Resolution

When the server is booting and reaches the grub menu example below.

      Red Hat Enterprise Linux Server (3.10.0-327.36.1.el7.x86_64) 7.2 (Maipo)  
      Red Hat Enterprise Linux Server (3.10.0-327.28.2.el7.x86_64) 7.2 (Maipo) 
      Red Hat Enterprise Linux Server (3.10.0-327.22.2.el7.x86_64) 7.2 (Maipo) 
                                                                               

      Use the ^ and v keys to change the selection.                       
      Press 'e' to edit the selected item, or 'c' for a command prompt.

Choose which kernel that needs to be edited, by using the arrow key to highlight the kernel version, then press the letter e key to edit the boot entry. The next screen should look similar to the below example of me selecting the 3.10.0-327.36.1.el7.x86_64 kernel for editing.

setparams 'Red Hat Enterprise Linux Server (3.10.0-327.36.1.el7.x86_64) 7.2 (M\ 
aipo)'                                                                         
                                                                               
        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'  a9bc46b\
9-2760-4c0a-98d9-700de2285293                                                  
        else                                                                   
          search --no-floppy --fs-uuid --set=root a9bc46b9-2760-4c0a-98d9-700d\v
e2285293                                                                       
        fi                                                                     
        linux16 /vmlinuz-3.10.0-327.36.1.el7.x86_64 root=/dev/mapper/rhel_unus\
ed-root ro console=tty0 crashkernel=128M rd.lvm.lv=rhel_unused/root rd.lvm.lv=\
rhel_unused/swap console=ttyS0,115200 LANG=en_US.UTF-8                         
        initrd16 /initramfs-3.10.0-327.36.1.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.

Once on this screen use the arrow keys to arrow down to the line starting with linux, for most systems it will be linux16, but it can also be just linux and linuxefi. Once the blinking cursor is on the linux16 line, press the End key, this will move the cursor to the end of the linux16 line. Then to boot into which ever target is desired, the below can be appended.

  • For booting into the emergency target.
systemd.unit=emergency.target
  • For booting into the multi-user target.
systemd.unit=multi-user.target

Once the above has been appended to the linux16 line it should look similar to the below example.

        linux16 /vmlinuz-3.10.0-327.36.1.el7.x86_64 root=/dev/mapper/rhel_unus\
ed-root ro console=tty0 crashkernel=128M rd.lvm.lv=rhel_unused/root rd.lvm.lv=\
rhel_unused/swap console=ttyS0,115200 LANG=en_US.UTF-8 systemd.unit=emergency.target

Once the parameter has been appended, press the Ctrl key and the x key at the same time to boot with the specified parameter.

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