要检查交换使用情况，我们可以使用以下命令：

1. free

# free
             total       used       free     shared    buffers     cached
Mem:       1004608     934036      70572          0      30124     769640
-/+ buffers/cache:     134272     870336
Swap:      1060248          0    1060248

2. /proc/meminfo

# grep Swap /proc/meminfo
SwapCached:            0 kB
SwapTotal:       1060248 kB
SwapFree:        1060248 kB

3. top

# top
.......
Mem:   1004608k total,   934780k used,    69828k free,    30124k buffers
Swap:  1060248k total,        0k used,  1060248k free,   770156k cached
.......

4. vmstat

# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0  69828  30124 770156    0    0    40   403   23   22  0  1 99  0  0