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Linux - Rescue/Recovery

Grub Lines

Emergency boot:

systemd.unit=emergency.target

Start execution step by step with confirmation:

systemd.confirm_spawn=true

Disable SELinux:

selinux=0

Procedures

Rescue from Grub

Start rescue from Grub menu:

# Depuis le menu Grub:
[e]

# Edit line with linux16 and add:
init=/bin/bash 

# Save with:
[ctrl-x]

# After boot, Remount /:
mount -o rw,remount /

Note

In some case, type the following command to create LVM special files in /dev:

vgmknode

Rescue from Boot CD-Rom

Rescue Mode after CD-Rom Boot:

# Change keyboard to FR
loadkeys fr

# Enable rootvg
vgchange -ay rootvg

# Create target directory
mkdir -p /target{,/usr,/home,/dev,/proc,/sys}

# Mount system FS
mount /dev/mapper/rootvg-root /target
mount /dev/mapper/rootvg-usr /target/usr
mount /dev/sda1 /target/boot
mount --bind /dev /target/dev
mount -t proc none /target/proc
mount -t sysfs none /target/sys

# Change root to target dir
chroot /target

Force FSCK in boot

RedHat 7|8

Edit this file:

/etc/default/grub

Add fsck.mode=forceand fsck.repair=yes options to GRUB_CMDLINE_LINUX vars:

# /etc/default/grub
...
GRUB_CMDLINE_LINUX="crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet fsck.mode=force fsck.repair=yes"

Rebuild grub2 file:

grub2-mkconfig -o /boot/grub2/grub.cfg

Scripts

Filesystem Corrupt

file -s /dev/dm* |grep errors |awk '{print $1}' |sed 's|:||'|sed 's|^.*/dm-||' |while read DM; do
  LV=$(dmsetup ls |grep "(253:$DM)" | awk '{print $1}')
  FS=$(df -ThP |grep -w $LV |awk '{print $NF}')
  [[ -z $FS ]] && FS=NOTMOUNTED
  echo $LV $FS
done

file -s /dev/dm* |grep errors |awk '{print $1}' |sed 's|:||'|sed 's|^.*/dm-||' |while read DM; do
  LV=$(dmsetup ls |grep "(253:$DM)" |awk '{print $1}')
  FS=$(df -ThP |grep -w $LV |awk '$NF != "NOTMOUNTED" {print $NF}')
  [[ -z $FS ]] && FS=NOTMOUNTED ;echo $LV $FS
done |awk '{print $NF}' |xargs -i lsof {} |awk '{print $2}' |sort -u |grep -v PID |xargs -i kill -9 {}

file -s /dev/dm* |grep errors |awk '{print $1}' |sed 's|:||'|sed 's|^.*/dm-||' |while read DM; do
  LV=$(dmsetup ls |grep "(253:$DM)" |awk '{print $1}')
  FS=$(df -ThP |grep -w $LV |awk '$NF != "NOTMOUNTED" {print $NF}')
  [[ -z $FS ]] && FS=NOTMOUNTED ;echo $LV $FS
done |awk '{print $NF}' |xargs -i umount {}

file -s /dev/dm* |grep errors |awk '{print $1}' |sed 's|:||'|sed 's|^.*/dm-||' |while read DM; do
  LV=$(dmsetup ls |grep "(253:$DM)" |awk '{print $1}')
  FS=$(df -ThP |grep -w $LV |awk '{print $NF}')
  [[ -z $FS ]] && FS=NOTMOUNTED ;echo $LV $FS
done |awk '$2 == "NOTMOUNTED" { print "fsck -y /dev/mapper/"$1 }' |sh

findmnt -kt ext4,xfs -O ro |sed -e 's|^|'`uname -n`';|' |grep -v TARGET
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