Tout d'abord merci pour votre aide !
Voici, MiCP, les trois réponses à tes lignes de commande :
Disque /dev/sda : 931,53 GiB, 1000204885504 octets, 1953525167 secteurs
Disk model: M3 Portable
Unités : secteur de 1 × 512 = 512 octets
Taille de secteur (logique / physique) : 512 octets / 4096 octets
taille d'E/S (minimale / optimale) : 4096 octets / 4096 octets
Type d'étiquette de disque : dos
Identifiant de disque : 0xebaed32c
Périphérique Amorçage Début Fin Secteurs Taille Id Type
/dev/sda1 * 64 1953520128 1953520065 931,5G 7 HPFS/N
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=1934224k,nr_inodes=483556,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
/dev/sdb7 on / type ext4 (rw,relatime,errors=remount-ro)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup2 on /sys/fs/cgroup/unified type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
efivarfs on /sys/firmware/efi/efivars type efivarfs (rw,nosuid,nodev,noexec,relatime)
bpf on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/rdma type cgroup (rw,nosuid,nodev,noexec,relatime,rdma)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,pagesize=2M)
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
/var/lib/snapd/snaps/gnome-calculator_730.snap on /snap/gnome-calculator/730 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/skype_118.snap on /snap/skype/118 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gtk-common-themes_1502.snap on /snap/gtk-common-themes/1502 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gnome-3-28-1804_116.snap on /snap/gnome-3-28-1804/116 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/discord_109.snap on /snap/discord/109 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/skype_123.snap on /snap/skype/123 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/canonical-livepatch_94.snap on /snap/canonical-livepatch/94 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/core_9066.snap on /snap/core/9066 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gimp_246.snap on /snap/gimp/246 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gnome-3-34-1804_27.snap on /snap/gnome-3-34-1804/27 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/core18_1668.snap on /snap/core18/1668 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/canonical-livepatch_95.snap on /snap/canonical-livepatch/95 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/spotify_41.snap on /snap/spotify/41 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/core18_1705.snap on /snap/core18/1705 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/core_8935.snap on /snap/core/8935 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gtk2-common-themes_9.snap on /snap/gtk2-common-themes/9 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gtk-common-themes_1506.snap on /snap/gtk-common-themes/1506 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gnome-logs_93.snap on /snap/gnome-logs/93 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gnome-characters_495.snap on /snap/gnome-characters/495 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/spotify_36.snap on /snap/spotify/36 type squashfs (ro,nodev,relatime,x-gdu.hide)
/var/lib/snapd/snaps/gimp_252.snap on /snap/gimp/252 type squashfs (ro,nodev,relatime,x-gdu.hide)
/dev/sdb1 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,nosuid,nodev,noexec,relatime)
tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=392336k,mode=700,uid=1000,gid=1000)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
/dev/fuse on /run/user/1000/doc type fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
/dev/sda1 on /media/marjo/Maxtor type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096,uhelper=udisks2)
/dev/sdb6 on /media/marjo/12bcf677-e123-42f6-8e0f-7b1c6c4262e7 type ext4 (rw,nosuid,nodev,relatime,uhelper=udisks2)
/dev/sdb5 on /media/marjo/donnees type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096,uhelper=udisks2)
TYPE SIZE NAME FSTYPE MOUNTPOINT LABEL UUID
disk 931,5G sda
part 931,5G └─sda1
ntfs /media/mar Maxtor
00BCC414BCC405DE
disk 465,8G sdb
part 599,9M ├─sdb1
│ vfat /boot/efi 0828-1609
part 29,3G ├─sdb2
│ ntfs 106A8ACB031D84AD
part 116,2G ├─sdb3
│ ntfs D6DCC52ADCC505A9
part 993M ├─sdb4
│ ntfs DA4E7B1E4E7AF31D
part 225G ├─sdb5
│ ntfs /media/mar donnees
│ 71D1905B6778F8A8
part 58,6G ├─sdb6
│ ext4 /media/mar 12bcf677-e123-42f6-8e0f-7b1c6c4262e7
part 29,3G ├─sdb7
│ ext4 / 023e0a8b-6771-4962-95be-4434de766b3d
part 5,9G └─sdb8
swap [SWAP] 8207262f-6dab-45e3-937c-3603f817a14b
disk 29,8G sdc
part 4G └─sdc1
OK, MiCP, c'est souvent ce que je fais (redémarrer plutôt qu'arrêter) mais comme je n'ai pas réussi à installer un menu dual boot, je suis obligée de rester à repérer le redémarrage pour appuyer sur F9, seul moyen d'afficher le menu de choix entre les OS... un peu lourd comme méthode 🙁
malbo, je vais aller voir les liens, merci !