One: Monitoring IO performance
Iostat-x disk usage
The last column indicates that the time taken for the disk is longer than
Iotop disk usage
Two: Free command
From left to right, total size, size used, remaining size
The remainder of the available=free+buffers/cached
Total=userd+free+buffers/cached
Three: PS command
View system process PS aux or ps-elf
PID: ID of the process
STAT: Indicates the status of the process, divided into the following types
D a process that cannot be interrupted (usually IO)
R Running Process
S has interrupted the process, usually, most of it is this state
T a process that has stopped or paused
W indicates that there are not enough memory page allocations
X already dead process (as if never appeared)
Z zombie process, can't kill, fight dead garbage process, generally does not appear
< high-priority processes
N Low-priority processes
L was locked in memory paging
S master Process
I Multithreading Process
-
Represents a process that is running in the foreground
is typically used with a pipe character to view a process or his quantity
PS aux|grep-c process name
results in minus 1 for the number of processes because grep itself is a process.
Four: View network status To print information such as network connection status, ports that are open to the system, routing tables, and so on.
Common commands: NETSTAT-LNP print which ports the current system launches
Netstat-an Print network connection status
Tips:
Netstat-an |awk '/^tcp/{++sta[$NF]} END {for (key in STA) print key, "\ T", Sta[key]} '
count the number of processes in all States
focus on the number of established
V: Linux under Grab pack Tcpdump
Install yum install-y tcpdump
Catch packet
tcpdump-nn-i eth0
The third and fourth columns show which ip+ port is connected to which ip+ port, and the following information is information about the packet
- I followed the device name
-nn to let the third and fourth columns appear as IP and port form, not plus display as host name + service name
-c Specifies the number of packages
-W writes the specified file, if not added, is displayed as data flow, not packet
host specified IP
Port specified ports
tcpdump-nn-i eth0 host 192.168.233.130 and Port 22-c 100-w 1.cap
View 1.cap can be Tcpdump-r 1.cap
also available To download to Windows with Wireshark view.
Wireshark
Install yum install-y wireshark
Usage tshark-n-t a-r http.request-t fields-e "Frame.time"-E "ip.src" -E "Http.host"-E "Http.request.method"-E "Http.request.uri"
This is similar to a Web Access log.
IO performance, free, PS, view network status, Linux catch-up package