How to create a custom menue in RHEL7

Solution Unverified - Updated

Environment

Red Hat Enterprise Linux7

Issue

When I created a new custom initramfs , how can I add the new kernel menu which includes the new initramfs?

Resolution

1. Create a new custom initramfs
How to rebuild the initial ramdisk image in Red Hat Enterprise Linux

2. Show sample entries using /etc/grub2.cfg by the following command.

# awk  '/^menuentry/,/\}/{if($1=="menuentry"){i++;print "####sample"i"####";print $0}else{print $0}}' /etc/grub2.cfg

For example:

# awk  '/^menuentry/,/\}/{if($1=="menuentry"){i++;print "####sample"i"####";print $0}else{print $0}}' /etc/grub2.cfg 
####sample1####
menuentry 'Red Hat Enterprise Linux Server, with Linux 3.10.0-229.el7.x86_64' --class red --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-229.el7.x86_64-advanced-65d647e7-c3c8-4330-9728-61378cb98639' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod xfs
        set root='hd0,msdos1'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  832273a3-e5eb-4bcb-9d4c-a049f88a6e93
        else
          search --no-floppy --fs-uuid --set=root 832273a3-e5eb-4bcb-9d4c-a049f88a6e93
        fi
        linux16 /vmlinuz-3.10.0-229.el7.x86_64 root=UUID=65d647e7-c3c8-4330-9728-61378cb98639 ro rd.lvm.lv=rhel/root crashkernel=auto  rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet debug rd.debug
        initrd16 /initramfs-3.10.0-229.el7.x86_64.img
}
####sample2####
menuentry 'Red Hat Enterprise Linux Server (3.10.0-862.9.1.el7.x86_64) 7.5 (Maipo) with debugging' --class fedora --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-862.9.1.el7.x86_64-advanced-08f35ea6-d950-447c-8e34-bf02b474c8b9' {
	load_video
	set gfxpayload=keep
:
:
:
:

3. create /etc/grub.d/40_custom using the abobe sample menuentry you chosed. The entry begins with the line starting with "menuentry" and ends with a line containing "}". Be careful not to change the 'exec tail -n +3 $0'

For example,

# cat /etc/grub.d/40_custom
!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry 'Red Hat Enterprise Linux Server, with Linux 3.10.0-229.el7.x86_64' --class red --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-229.el7.x86_64-advanced-65d647e7-c3c8-4330-9728-61378cb98639' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod xfs
        set root='hd0,msdos1'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  832273a3-e5eb-4bcb-9d4c-a049f88a6e93
        else
          search --no-floppy --fs-uuid --set=root 832273a3-e5eb-4bcb-9d4c-a049f88a6e93
        fi
        linux16 /vmlinuz-3.10.0-229.el7.x86_64 root=UUID=65d647e7-c3c8-4330-9728-61378cb98639 ro rd.lvm.lv=rhel/root crashkernel=auto  rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet debug rd.debug
        initrd16 /initramfs-3.10.0-229.el7.x86_64.img
}

4. Change the title after menuentry:

menuentry 'Red Hat Enterprise Linux Server, with Linux 3.10.0-229.el7.x86_64'

Change to,

menuentry 'Red Hat Enterprise Linux Server, with Linux 3.10.0-229.el7.x86_64 - TEST'

5. Change the menuentry_id_option:

gnulinux-3.10.0-229.el7.x86_64-advanced-65d647e7-c3c8-4330-9728-61378cb98639

Change to,

gnulinux-3.10.0-229.el7.x86_64-TEST

6. Change the initramfs file name in the line starting with linux16. 

 linux16 /vmlinuz-3.10.0-229.el7.x86_64 root=UUID=65d647e7-c3c8-4330-9728-61378cb98639 ro rd.lvm.lv=rhel/root crashkernel=auto  rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet debug rd.debug
        initrd16 /initramfs-3.10.0-229.el7.x86_64.img

Change to,

linux16 /vmlinuz-3.10.0-229.el7.x86_64 root=UUID=65d647e7-c3c8-4330-9728-61378cb98639 ro rd.lvm.lv=rhel/root crashkernel=auto  rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet debug rd.debug
        initrd16 /initramfs-3.10.0-229.el7.x86_64-TEST.img

7. Update /boot/grub2/grub.cfg to apply the changed config file:

  • On BIOS-based machines: ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
  • On UEFI-based machines: ~]# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

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