System activity reporting tool.
The sar command is a system activity reporting tool under Linux that displays specified operating system state counters to the standard output device. The sar tool samples the current state of the system and then expresses the system's current operating state by calculating data and ratios. Its characteristic is that it can continuously sample the system to obtain a large amount of sampling data. Both sampling data and analysis results can be stored in files, and it consumes very few system resources when used.
sar(options)(parameters)
-A: Displays all report information.
-b: Displays I/O rates.
-B: Displays paging statistics.
-c: Displays process creation activity.
-d: Displays the status of each block device.
-e: Sets the end time for the report.
-f: Extracts the report from the specified file.
-i: Sets the interval for refreshing status information.
-n: Reports network statistics.
-P: Reports status for each CPU.
-R: Displays memory statistics.
-u: Displays CPU utilization.
-v: Displays the status of inodes, files, and other kernel tables.
-w: Displays swapping statistics.
-x: Displays the status of a given process.
-r: Displays output in pages, with a maximum of 100 lines per page.
-o: Output options; specifies the columns to be displayed. E.g., `-o mrk,prt,cvg` displays CPU usage, PIDs, disk usage, and network traffic.
-t: Timestamp option; adds timestamps to the output.
-s: Statistics option; specifies the type of statistics to display. E.g., `-s us,ms` displays average values for us and ms CPU time.
-c: Specifies the command to be sent. E.g., `-c ls` displays the list of files and subdirectories in the current directory.
Check memory and swap space utilization:
sar -r
Linux 2.4.20-8 (www.jsdig.com) 20130503
12:00:01 AM kbmemfree kbmemused %memused
kbmemshrd kbbuffers kbcached
12:10:00 AM 240468 1048252 81.34
0 133724 485772
12:20:00 AM 240508 1048212 81.34
0 134172 485600
…
08:40:00 PM 934132 354588 27.51
0 26080 185364
Average: 324346 964374 74.83
0 96072 467559
The kbmemfree and kbmemused fields show unused and used memory, respectively, followed by the percentage of used memory (%memused). The kbbuffers and kbcached fields show the amount of data accessed by buffers and the system cache, respectively, in KB.
Monitor system components for 10 minutes and sort the data:
sar -o temp 60 10
Display memory and network statistics stored in the daily data file "sa16":
sar -r -n DEV -f /var/log/sa/sa16
Check CPU utilization:
sar -t
Check disk utilization:
sar -s disk
Check network traffic:
sar -s nic
Send a command to a system service:
sar -c ls
Display the current system timestamp:
sar -t +%s
These are just a few examples of the sar command; you can choose different options and parameters based on your specific needs.
Note: The output of the sar command may vary depending on system performance. For more accurate results, consider monitoring when system performance is optimal.