Comprehensive and Detailed Explanation From Exact Extract of Forescout Platform Administration and Deployment:
The correct command to monitor system memory and CPU load with 5 second update intervals is vmstat 5. According to the official Linux documentation and Forescout CLI reference materials, the vmstat command uses a straightforward syntax where the first numerical parameter specifies the delay interval in seconds.
vmstat Command Syntax:
The vmstat (Virtual Memory Statistics) command uses the following syntax:
bash
vmstat [options] [delay] [count]
Where:
delay - The time interval (in seconds) between updates
count - The number of updates to display (optional; if omitted, displays indefinitely)
vmstat 5 Command:
When you execute vmstat 5:
Updates are displayed every 5 seconds
Continues indefinitely until manually stopped
Shows memory and CPU statistics in each update
Example output:
text
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 1166396 70768 2233228 0 0 0 13 10 24 0 0 100 0 0
0 0 0 1165568 70776 2233352 0 0 0 8 121 224 0 0 99 0 0
0 0 0 1166608 70784 2233352 0 0 0 53 108 209 0 0 100 0 0
Each line represents a new report generated at 5-second intervals.
Memory and CPU Information Provided:
The vmstat output includes:
Memory Columns:
free - Amount of idle memory
buff - Amount of memory used as buffers
cache - Amount of memory used as cache
swpd - Amount of virtual memory used
si/so - Memory swapped in/out
CPU Columns:
us - Time spent running user code
sy - Time spent running kernel code
id - Time spent idle
wa - Time spent waiting for I/O
st - Time stolen from virtual machine
Why Other Options Are Incorrect:
A. watch -t 5 vmstat - Incorrect syntax; -t removes headers, not set intervals; interval flag is -n, not -t
C. vmstat -t 5 - The -t option adds a timestamp to output, but doesn't set the interval; the 5 would be ignored
D. watch uptime - The uptime command displays system uptime and load average but not detailed memory/CPU stats; watch requires -n flag for interval specification
E. watch -n 10 vmstat - While syntactically valid, this uses a 10-second interval, not 5 seconds; also unnecessary since vmstat already supports delay parameter directly
Additional vmstat Examples:
According to documentation:
bash
vmstat 5 5 # Display 5 updates at 5-second intervals
vmstat 1 10 # Display 10 updates at 1-second intervals
vmstat -t 5 5 # Display 5 updates every 5 seconds WITH timestamps
First Report Note:
According to the documentation:
"When you run vmstat without any parameters, it shows system values based on the averages for each element since the server was last rebooted. These results are not a snapshot of current values."
The first report with vmstat 5 shows averages since last reboot; subsequent reports show statistics for each 5-second interval.
Referenced Documentation:
Linux vmstat Command Documentation
RedHat vmstat Command Guide
Oracle Solaris vmstat Manual
Microsoft Azure Linux Troubleshooting Guide
IBM AIX vmstat Documentation
