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適当な場所にファイルを作成． ここでは2GB分

$ sudo dd if=/dev/zero of=/var/tmp/swap bs=1M count=2048

swap設定

$ sudo chmod 600 /var/tmp/swap  # rootのみ読み書き
$ sudo mkswap /var/tmp/swap     # swap初期化
$ sudo swapon /var/tmp/swap     # swapに割当
$ free -h                       # swap確認
              total        used        free      shared  buff/cache   available
Mem:          966Mi       303Mi        62Mi        12Mi       600Mi       501Mi
Swap:         2.0Gi       0.0Ki       2.0Gi
$ sudo swapoff /var/tmp/swap    # swapから取り外し

永続化

$ sudo vi /etc/fstab                       # /etc/fatab 修正
$ sudo git -C /etc diff HEAD~ /etc/fstab
diff --git a/fstab b/fstab
index d1ac1c3..01c9c0e 100644
--- a/fstab
+++ b/fstab
@@ -1,5 +1,6 @@
 LABEL=cloudimg-rootfs  /        ext4   defaults        0 1
 LABEL=UEFI     /boot/efi       vfat    umask=0077      0 1
+/var/tmp/swap  none    swap    pri=-1  0 0

 # CLOUD_IMG: This file was created/modified by the Cloud Image build process
 ######################################
$ sudo swapon -av                          # swapを手動で反映(次回起動時からは自動的に反映される)
swapon: /var/tmp/swap: found signature [pagesize=4096, signature=swap]
swapon: /var/tmp/swap: pagesize=4096, swapsize=2147483648, devsize=2147483648
swapon /var/tmp/swap
$ free
              total        used        free      shared  buff/cache   available
Mem:         989340      308556       71368       12880      609416      517280
Swap:       2097148           0     2097148

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