ディスク、ファイルシステム、マウントの自動化

lsblkとfdiskでブロックデバイスを理解する

#!/usr/bin/env bash
# Inspect all block devices and their UUIDs
set -euo pipefail

echo '=== Block Device Tree ==='
lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINT,UUID

echo ''
echo '=== Partition Table Details ==='
sudo fdisk -l 2>/dev/null | grep -E '^Disk |^/dev/'

echo ''
echo '=== UUID Lookup via blkid ==='
sudo blkid | awk -F: '{print $1}' | while read -r dev; do
  uuid=$(sudo blkid -s UUID -o value "$dev" 2>/dev/null || echo 'N/A')
  fstype=$(sudo blkid -s TYPE -o value "$dev" 2>/dev/null || echo 'unknown')
  printf '%-20s UUID=%-38s TYPE=%s\n' "$dev" "$uuid" "$fstype"
done

dfとduでディスク容量を確認する

#!/usr/bin/env bash
# Alert if any mounted filesystem exceeds a usage threshold
set -euo pipefail

THRESHOLD=80   # percent

echo 'Checking filesystem usage...'
df -h --output=source,pcent,target | tail -n +2 | while IFS= read -r line; do
  device=$(awk '{print $1}' <<< "$line")
  pct=$(awk '{print $2}' <<< "$line" | tr -d '%')
  mount=$(awk '{print $3}' <<< "$line")

  # Skip pseudo filesystems
  [[ "$device" == tmpfs* || "$device" == devtmpfs* ]] && continue

  if (( pct >= THRESHOLD )); then
    echo "WARNING: $device mounted at $mount is ${pct}% full" >&2
  else
    echo "OK: $device at $mount is ${pct}% used"
  fi
done

/etc/fstabを読み取り解析する

#!/usr/bin/env bash
# Parse /etc/fstab and display non-comment entries in a readable table
set -euo pipefail

FSTAB=/etc/fstab

printf '%-40s %-20s %-10s %s\n' 'DEVICE' 'MOUNTPOINT' 'FSTYPE' 'OPTIONS'
printf '%s\n' '-------------------------------------------------------------------------------------'

while IFS= read -r line; do
  # Skip blank lines and comments
  [[ -z "$line" || "$line" =~ ^[[:space:]]*# ]] && continue

  read -r device mountpt fstype options _dump _pass <<< "$line"
  printf '%-40s %-20s %-10s %s\n' "$device" "$mountpt" "$fstype" "$options"
done < "$FSTAB"

fstabエントリを安全に追加する

#!/usr/bin/env bash
# Safely append a new entry to /etc/fstab (idempotent)
set -euo pipefail

DEVICE_PATH='/dev/sdb1'
MOUNTPOINT='/mnt/data'
FSTYPE='ext4'
OPTIONS='defaults,nofail'
FSTAB='/etc/fstab'

# Resolve UUID for stable identification
UUID=$(sudo blkid -s UUID -o value "$DEVICE_PATH")
if [[ -z "$UUID" ]]; then
  echo "ERROR: Could not resolve UUID for $DEVICE_PATH" >&2
  exit 1
fi

ENTRY="UUID=$UUID  $MOUNTPOINT  $FSTYPE  $OPTIONS  0  2"

# Idempotency: skip if UUID already referenced in fstab
if grep -qsF "UUID=$UUID" "$FSTAB"; then
  echo "INFO: fstab already contains UUID=$UUID — skipping."
  exit 0
fi

# Backup
cp -p "$FSTAB" "${FSTAB}.bak.$(date +%Y%m%d%H%M%S)"

# Create mountpoint if needed
sudo mkdir -p "$MOUNTPOINT"

# Append entry
echo "$ENTRY" | sudo tee -a "$FSTAB" > /dev/null
echo "INFO: Added: $ENTRY"

# Validate
sudo findmnt --verify --verbose || echo 'WARNING: findmnt verify reported issues'

スクリプトでファイルシステムをマウントおよびアンマウントする

#!/usr/bin/env bash
# Mount a device only if not already mounted; log outcome
set -euo pipefail

DEVICE='/dev/sdb1'
MOUNTPOINT='/mnt/data'

log() { logger -t disk-mount "$*"; echo "[$(date '+%F %T')] $*"; }

# Check if already mounted
if mountpoint -q "$MOUNTPOINT"; then
  log "INFO: $MOUNTPOINT is already mounted — nothing to do."
  exit 0
fi

# Ensure mountpoint directory exists
sudo mkdir -p "$MOUNTPOINT"

# Attempt mount
if sudo mount "$DEVICE" "$MOUNTPOINT"; then
  log "OK: Mounted $DEVICE at $MOUNTPOINT"
else
  log "ERROR: Failed to mount $DEVICE at $MOUNTPOINT"
  exit 1
fi

# Show what is now mounted there
df -h "$MOUNTPOINT"

LVM入門：Physical Volume、Volume Group、Logical Volume

LVMボリュームの作成をスクリプトで自動化する

#!/usr/bin/env bash
# Automate LVM setup: PV -> VG -> LV -> mkfs -> mount
set -euo pipefail

DISK='/dev/sdc'          # raw disk, no existing partitions
VG_NAME='vg_appdata'
LV_NAME='lv_appdata'
LV_SIZE='10G'
MOUNTPOINT='/mnt/appdata'
FSTYPE='xfs'

echo "[1/6] Initializing Physical Volume on $DISK"
sudo pvcreate -y "$DISK"

echo "[2/6] Creating Volume Group: $VG_NAME"
sudo vgcreate "$VG_NAME" "$DISK"

echo "[3/6] Creating Logical Volume: $LV_NAME (${LV_SIZE})"
sudo lvcreate -y -L "$LV_SIZE" -n "$LV_NAME" "$VG_NAME"

echo "[4/6] Formatting as $FSTYPE"
sudo mkfs."$FSTYPE" "/dev/$VG_NAME/$LV_NAME"

echo "[5/6] Mounting at $MOUNTPOINT"
sudo mkdir -p "$MOUNTPOINT"
sudo mount "/dev/$VG_NAME/$LV_NAME" "$MOUNTPOINT"

echo "[6/6] Done. Disk usage:"
df -h "$MOUNTPOINT"

# Show LVM summary
vgs && lvs

Logical Volumeをオンラインで拡張する

#!/usr/bin/env bash
# Extend an LV and its xfs filesystem online
set -euo pipefail

VG_NAME='vg_appdata'
LV_NAME='lv_appdata'
EXTEND_BY='5G'
LV_DEV="/dev/$VG_NAME/$LV_NAME"

# Confirm VG has enough free space
FREE_GB=$(vgs --noheadings --units g -o vg_free "$VG_NAME" | tr -d ' g')
echo "VG free space: ${FREE_GB}G"
if (( $(echo "$FREE_GB < 5" | bc -l) )); then
  echo 'ERROR: Not enough free space in VG' >&2
  exit 1
fi

echo "Extending LV by $EXTEND_BY..."
sudo lvextend -L "+${EXTEND_BY}" "$LV_DEV"

echo 'Growing xfs filesystem online...'
sudo xfs_growfs "$LV_DEV"

echo 'New size:'
df -h "$LV_DEV"
lvs "$LV_DEV"

ファイルシステムの作成とフォーマット

#!/usr/bin/env bash
# Format a partition and assign a label; print resulting UUID
set -euo pipefail

PARTITION='/dev/sdb1'
FSTYPE='ext4'
LABEL='appdata'

# Safety check: refuse to format a currently mounted device
if findmnt --source "$PARTITION" > /dev/null 2>&1; then
  echo "ERROR: $PARTITION is currently mounted. Unmount first." >&2
  exit 1
fi

echo "Formatting $PARTITION as $FSTYPE with label '$LABEL'..."
sudo mkfs."$FSTYPE" -L "$LABEL" -F "$PARTITION"

# Retrieve and display the new UUID
NEW_UUID=$(sudo blkid -s UUID -o value "$PARTITION")
echo "Formatted successfully."
echo "Label : $LABEL"
echo "UUID  : $NEW_UUID"
echo "Use this in fstab: UUID=$NEW_UUID  /mnt/$LABEL  $FSTYPE  defaults,nofail  0  2"

autofsでNFSマウントを自動化する

#!/usr/bin/env bash
# Generate an autofs NFS map file from a share list and reload autofs
set -euo pipefail

NFS_SERVER='192.168.1.50'
AUTO_MAP='/etc/auto.nfs'
AUTO_MASTER='/etc/auto.master'
MOUNT_BASE='/nfs'

# Define shares: localname:remote_path
declare -A SHARES=(
  [homes]='/export/homes'
  [media]='/export/media'
  [backups]='/export/backups'
)

# Write map file
{
  echo '# Generated by disk-automation script'
  for localname in "${!SHARES[@]}"; do
    remote="${SHARES[$localname]}"
    echo "$localname  -rw,soft,timeo=30  ${NFS_SERVER}:${remote}"
  done
} | sudo tee "$AUTO_MAP" > /dev/null

echo "Wrote $AUTO_MAP"

# Ensure master map references this file
if ! grep -qF "$AUTO_MAP" "$AUTO_MASTER"; then
  echo "$MOUNT_BASE  $AUTO_MAP" | sudo tee -a "$AUTO_MASTER" > /dev/null
  echo "Updated $AUTO_MASTER"
fi

sudo systemctl reload autofs && echo 'autofs reloaded'

安全なバックアップのためのLVMスナップショット

#!/usr/bin/env bash
# Create an LVM snapshot, back up via tar, then remove snapshot
set -euo pipefail

VG='vg_appdata'
ORIGIN_LV='lv_appdata'
SNAP_LV='lv_appdata_snap'
SNAP_SIZE='2G'
SNAP_MOUNT='/mnt/snap_backup'
BACKUP_DEST='/var/backups/appdata'
DATESTAMP=$(date +%Y%m%d_%H%M%S)

trap 'sudo umount "$SNAP_MOUNT" 2>/dev/null; sudo lvremove -f "/dev/$VG/$SNAP_LV" 2>/dev/null' ERR EXIT

echo '[1] Creating snapshot...'
sudo lvcreate -s -n "$SNAP_LV" -L "$SNAP_SIZE" "/dev/$VG/$ORIGIN_LV"

echo '[2] Mounting snapshot read-only...'
sudo mkdir -p "$SNAP_MOUNT"
sudo mount -o ro "/dev/$VG/$SNAP_LV" "$SNAP_MOUNT"

echo '[3] Archiving to backup destination...'
sudo mkdir -p "$BACKUP_DEST"
sudo tar -czf "$BACKUP_DEST/appdata_${DATESTAMP}.tar.gz" -C "$SNAP_MOUNT" .

echo '[4] Cleaning up snapshot...'
sudo umount "$SNAP_MOUNT"
sudo lvremove -f "/dev/$VG/$SNAP_LV"

echo "Backup complete: $BACKUP_DEST/appdata_${DATESTAMP}.tar.gz"

理解度チェック：安全なfstabとマウントの自動化

レッスンのまとめ：ディスク、ファイルシステム、マウントの自動化