On the previous post, i have teach you on how to check the memory usage on linux virtual Private Server (VPS) but only top command had provide real-time information and updates . This quick post will covers on how to check realtime RAM memory usage available in Linux VPS using watch command. Watch runs command repeatedly, displaying its output change over time or at regular intervals. Watch will run until interrupted. This command has been tested on Redhat Linux Enterprise 6 (RHEL 6) and may working on CentOS 6.x as well.
The basic syntax of watch is :
# watch [option(s)] command
1. Check memory usage using “top” command. Watch command not required for top command as top will update the result periodically. :
[root@rhel6 ~]# top
2. Check memory usage using “/proc/meminfo” with watch command :
[root@rhel6 ~]# watch -n 1 cat /proc/meminfo
Output :
Every 1.0s: cat /proc/meminfo Mon Oct 15 13:48:17 2012 MemTotal: 1031320 kB MemFree: 626372 kB Buffers: 58576 kB Cached: 217004 kB SwapCached: 0 kB Active: 148516 kB Inactive: 164708 kB Active(anon): 37816 kB Inactive(anon): 84 kB Active(file): 110700 kB Inactive(file): 164624 kB Unevictable: 0 kB Mlocked: 0 kB HighTotal: 141256 kB HighFree: 280 kB LowTotal: 890064 kB LowFree: 626092 kB SwapTotal: 2064376 kB SwapFree: 2064376 kB Dirty: 4 kB Writeback: 0 kB AnonPages: 37652 kB Mapped: 19096 kB Shmem: 264 kB Slab: 81048 kB SReclaimable: 62096 kB SUnreclaim: 18952 kB .. .. ..
3. Check memory usage using “free” with watch command :
[root@rhel6 ~]# watch -n 1 free
Output :
Every 1.0s: free Mon Oct 15 13:47:26 2012
total used free shared buffers cached
Mem: 1031320 404548 626772 0 58564 217004
-/+ buffers/cache: 128980 902340
Swap: 2064376 0 2064376
4. Check memory usage using “vmstat” with watch command :
[root@rhel6 ~]# watch -n 1 vmstat
Output :
Every 1.0s: vmstat Mon Oct 15 13:46:44 2012 procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 626280 58552 217004 30 0 0 14 46 73 0 1 98 1 0
