1.查看

root@ubt01:~# free -m
              total        used        free      shared  buff/cache   available
Mem:           3908        3211         244           1         451         415
Swap:          3907           0        3907
root@ubt01:~# cat /proc/swaps 
Filename                                Type            Size    Used    Priority
/swap.img                               file            4001788 0       -2

2.停止

root@ubt01:~# swapoff /swap.img 

3.删除

root@ubt01:~# rm /swap.img 

4.重建

#bs x count = 1024 × 1000000 = 1G  (bs:块大小为1k)  
root@ubt01:~# dd if=/dev/zero of=/swap.img bs=1024 count=1000000
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB, 977 MiB) copied, 1.95864 s, 523 MB/s

5.启用

root@ubt01:~# chmod 600 /swap.img 
root@ubt01:~# mkswap -f /swap.img 
Setting up swapspace version 1, size = 976.6 MiB (1023995904 bytes)
no label, UUID=087b7795-e265-49c3-9791-f5074dc99c7f
root@ubt01:~# swapon /swap.img

6.检查

root@ubt01:~# free -m
              total        used        free      shared  buff/cache   available
Mem:           3908        3204         119           1         583         467
Swap:           976           0         976
root@ubt01:~# cat /proc/swaps 
Filename                                Type            Size    Used    Priority
/swap.img                               file            999996  0       -2

7.如修改了文件名或目录，需修改下如下文件

root@ubt01:~# cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/vg0/lv-0 during curtin installation
/dev/disk/by-id/dm-uuid-LVM-J3pZ9NXqLtjpHh2E9gxK6gwIjX2wbwClYXWGdy0T86oN3b08mlAYGN8fJfn5G16R / ext4 defaults 0 0
# /boot was on /dev/sda2 during curtin installation
/dev/disk/by-uuid/f8e5cea8-4a19-4558-ba16-0be35aeb5f6d /boot ext4 defaults 0 0
/swap.img       none    swap    sw      0       0
root@ubt01:~#