[forlong401@dfdsfdsfs ~]# cd /var/

[forlong401@dfdsfdsfs var]# dd if=/dev/zero of=swapfile bs=1024 count=2048000

记录了2048000+0 的读入

记录了2048000+0 的写出

2097152000字节(2.1 GB)已复制，61.357 秒，34.2 MB/秒

[forlong401@dfdsfdsfs var]# mkswap swapfile

mkswap: swapfile: warning: don‘t erase bootbits sectors

        on whole disk. Use -f to force.

Setting up swapspace version 1, size = 2047996 KiB

no label, UUID=fdafdsfdsb-3sfdb-4sfdc-bfdfd7-8sdfsafds89

[forlong401@dfdsfdsfs var]# swapon swapfile

[forlong401@dfdsfdsfs var]# swapon -s

Filename Type Size Used Priority

/var/swapfile                           file 2047996 0 -1

[forlong401@dfdsfdsfs var]# echo "/var/swapfile swap swap defaults 0 0">>/etc/fstab

[forlong401@dfdsfdsfs var]# free -m

             total       used       free     shared    buffers     cached

Mem:           488        478         10          0          4        132

-/+ buffers/cache:        341        147

Swap:         1999          0       1999

[forlong401@dfdsfdsfs var]# top -a

top - 21:04:55 up 3 days, 21:06,  2 users,  load average: 0.05, 0.25, 0.13

Tasks: 113 total,   1 running, 112 sleeping,   0 stopped,   0 zombie

Cpu(s):  0.3%us,  0.0%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st

Mem:    52423423k total,   424234232k used,     942343k free,     523424k buffers

Swap:  2047996k total,        0k used,  2047996k free,   136088k cached

3.删除swap分区

       有时可能会需要删除swap分区，该如何正确进行删除分区哪?

• 首先停止swap分区
  

  swapoff   /swap/swap 

  
  

• 删除swap分区文件
  

  rm -rf /swap/swap 

  
  

• 删除"/etc/swap"指定文件
  

  sed  -i "/‘\/swa\/swap   swap   swap  defaults 0 0‘//"  /etc/fstab 

  
  

     这样就可以手工添加和删除swap分区。