{"id":553,"date":"2012-11-07T12:56:49","date_gmt":"2012-11-07T11:56:49","guid":{"rendered":"http:\/\/clark.tipistrani.it\/?p=553"},"modified":"2012-11-18T11:07:58","modified_gmt":"2012-11-18T10:07:58","slug":"ripristino-di-grub2","status":"publish","type":"post","link":"http:\/\/clark.tipistrani.it\/?p=553","title":{"rendered":"Ripristino di grub2"},"content":{"rendered":"

Capita a volte specie sui portatili di avere macchine in dual boot<\/a>\u00a0 tipicamente il Windows che c’e’ instalalto e una distro Linux, capita anche\u00a0 per n+1 ragioni capita di dover reinstallare uno dei sistemi operativi, se il SO \u00e8 il Linux non ci sono particolari problemi al contrario se \u00e8 Windows si, infatti Windows riscrive il MBR<\/a> cancellando grub e la possibilit\u00e0 di scegliere quale sistema avviare cosa che mi e’ successa proprio in questo periodo avendo dovuto reinstallare XP Pro sul mio Dell LATITUDE D830.
\nUn sistema per ripistinare il grub e la distro Linux sparita \u00e8 il seguente, facciamo boot con una live distro (ho usato una Knoppix<\/a>), per mia comodit\u00e0\/abitudine ho usato le opzioni di boot knoppix\u00a0 lang=it 2\u00a0 che in sostanza significa carica la map italiana della tastiera e parti a runlevel 2 AKA a linea di comando.
\nSi tratta adesso di capire dove sia linux sul disco fisso cosa che si pu\u00f2 leggere con un fdisk -l (il flag \u00e8 meno elle NON meno uno) il risultato e’ il seguente:<\/p>\n

 <\/p>\n

root@Microknoppix:\/# fdisk -l<\/p>\n

Disk \/dev\/sda: 120.0 GB, 120034123776 bytes
\n255 heads, 63 sectors\/track, 14593 cylinders
\nUnits = cylinders of 16065 * 512 = 8225280 bytes
\nSector size (logical\/physical): 512 bytes \/ 512 bytes
\nI\/O size (minimum\/optimal): 512 bytes \/ 512 bytes
\nDisk identifier: 0x5eff4ed2<\/p>\n

Device Boot\u00a0\u00a0\u00a0\u00a0\u00a0 Start\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 End\u00a0\u00a0\u00a0\u00a0\u00a0 Blocks\u00a0\u00a0 Id\u00a0 System
\n\/dev\/sda1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 15\u00a0\u00a0\u00a0\u00a0\u00a0 120456\u00a0\u00a0 de\u00a0 Dell Utility
\n\/dev\/sda2\u00a0\u00a0 *\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 16\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6543\u00a0\u00a0\u00a0 52436160\u00a0\u00a0\u00a0 7\u00a0 HPFS\/NTFS
\n\/dev\/sda3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6544\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6580\u00a0\u00a0\u00a0\u00a0\u00a0 292864\u00a0\u00a0 83\u00a0 Linux
\n\/dev\/sda4\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6580\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 14594\u00a0\u00a0\u00a0 64369665\u00a0\u00a0\u00a0 5\u00a0 Extended
\n\/dev\/sda5\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6580\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6823\u00a0\u00a0\u00a0\u00a0 1951744\u00a0\u00a0 83\u00a0 Linux
\n\/dev\/sda6\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6823\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7006\u00a0\u00a0\u00a0\u00a0 1464320\u00a0\u00a0 82\u00a0 Linux swap \/ Solaris
\n\/dev\/sda7\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 7006\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 8829\u00a0\u00a0\u00a0 14647296\u00a0\u00a0 83\u00a0 Linux
\n\/dev\/sda8\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 8829\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 9072\u00a0\u00a0\u00a0\u00a0 1951744\u00a0\u00a0 83\u00a0 Linux
\n\/dev\/sda9\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 9072\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 14594\u00a0\u00a0\u00a0 44350464\u00a0\u00a0 83\u00a0 Linux
\nroot@Microppix:\/#<\/p>\n

le partizioni che mi\u00a0 interessano sono da \/dev\/sda3 in poi, infatti la \/dev\/sda3 \u00e8 la \/boot la \/dev\/sda5 e’ la \/\u00a0 la \/dev\/sda7 \u00e8 la \/usr\u00a0 e la \/dev\/sda8 \u00e8 la \/var.<\/p>\n

Monto \/dev\/sda5 \/in \/media\/sda5<\/p>\n

mount \/dev\/sda1 \/media\/sda5
\na seguire monto \/dev \/proc\/\u00a0 \/sys\u00a0 in sda5<\/p>\n

mount –bind\u00a0 \/dev\/ \/media\/sda5\/dev
\nmount –bind \/proc \/media\/sda5\/proc
\nmount –bind \/sys \/media\/sda5\/sys<\/p>\n

a questo punto mi sposto in \/media\/sda5 e mi chroot li
\ncd \/media\/sda5
\nchroot .
\nadesso sono in chroot sulla \/ del mio disco fisso\u00a0 dove \u00e8 instllata la mia Debian, e pocedo a montare le altre partizioni con:
\nmount \/dev\/sda3 \/boot
\nmount \/dev\/sda7 \/usr
\nmount \/dev\/sda8 \/var<\/p>\n

Reinstallo grub con:<\/p>\n

grub-install \/dev\/sda e quindi update-grub2<\/p>\n

se si ricevono messaggi di errore provare con<\/p>\n

grub-install –recheck \/dev\/sda<\/p>\n

A questo punto exit per uscire dalla chroot (CTRL-D \u00e8 la stessa cosa) smontare tutte le partizioni con umount e dare reboot il grub e’ di nuovo installato nell MBR e sar\u00e0 posibile sceglierecon che Sistema Operativo partire.<\/p>\n

<\/pre>\n","protected":false},"excerpt":{"rendered":"
Capita a volte specie sui portatili di avere macchine in dual boot\u00a0 tipicamente il Windows che c’e’ instalalto e una distro Linux, capita anche\u00a0 per n+1 ragioni capita di dover reinstallare uno dei sistemi operativi, se il SO \u00e8 il Linux non ci sono particolari problemi al contrario se \u00e8 Windows si, infatti Windows riscrive […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,7,6],"tags":[],"class_list":["post-553","post","type-post","status-publish","format-standard","hentry","category-linux","category-sistemi-operativi","category-work"],"_links":{"self":[{"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/posts\/553","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=553"}],"version-history":[{"count":12,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/posts\/553\/revisions"}],"predecessor-version":[{"id":560,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=\/wp\/v2\/posts\/553\/revisions\/560"}],"wp:attachment":[{"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=553"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=553"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/clark.tipistrani.it\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=553"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}