How many Linux can one have

[Ralf Mardorf]

You can have as much distros with as much kernels installed as you want.
There isn't a limit.

My current machine does look like that:

[rocketmouse at archlinux ~]$ grep menu /mnt/debi386/boot/grub/grub.cfg 
  set menu_color_normal=cyan/blue
  set menu_color_highlight=white/blue
menuentry 'Debian,                Linux 3.8.13-rt14-pae-rocketmouse-2' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian,                Linux 3.12-0.bpo.1-rt-686-pae' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian,                Linux 3.8.13-rt14-pae-rocketmouse' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 3.2.0-4-rt-686-pae' --class debian --class gnu-linux --class gnu --class os {
menuentry 'Debian GNU/Linux, with Linux 3.2.0-4-rt-686-pae (recovery mode)' --class debian --class gnu-linux --class gnu --class os {
        menuentry 'Kubuntu Saucy,         kernel 3.8.13-rt14-1-rt' --class kubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.8.13-rt14-1-rt-advanced-cb253c90-4261-4114-95e5-32a59c85c162' {
        menuentry 'Kubuntu Saucy,         kernel 3.6.5-rt14' --class kubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.6.5-rt14-advanced-cb253c90-4261-4114-95e5-32a59c85c162' {
        menuentry 'Kubuntu Saucy,         kernel 3.11.0-14-lowlatency threadirqs' --class kubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-cb253c90-4261-4114-95e5-32a59c85c162' {
        menuentry 'Kubuntu Saucy,         kernel 3.11.0-14-lowlatency single' --class kubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-cb253c90-4261-4114-95e5-32a59c85c162' {
menuentry 'Arch Linux Rt' {
menuentry 'Arch Linux Rt LTS' {
menuentry 'Arch Linux Rt nohz=off' {
menuentry 'Arch Linux' {
menuentry 'Arch Linux Fallback' {
menuentry 'openSUSE 11.2,         Kernel 2.6.31.6-rt19' {
menuentry "FreeBSD"{
menuentry "XP"{
menuentry 'Ubuntu Quantal,        kernel 3.6.5-rt14' {
menuentry 'Ubuntu Quantal,        kernel 3.10.9-rt5 experimental' {
menuentry 'Ubuntu Quantal,        kernel 3.5.0-18-lowlatency threadirqs' {
menuentry 'Ubuntu Quantal,        kernel 3.5.0-18-lowlatency (recovery mode)' {
menuentry 'Ubuntu Studio Quantal, Kernel 3.6.5-rt14' {
menuentry 'Ubuntu Studio Quantal, Kernel 3.5.0-18-lowlatency threadirqs' {
menuentry 'Ubuntu Studio Precise, Kernel 3.0.30 threadirqs' {
menuentry 'Ubuntu Studio Precise, Kernel 3.2.0-23-lowlatency threadirqs' {
menuentry 'Edubuntu 10.10,        Kernel 2.6.33.9-rt31' {
menuentry 'Ubuntu Studio Oz,      Kernel 3.0.0-17-generic' {
menuentry 'Ubuntu Studio Oz,      Kernel 3.0.0-20-generic' {