30 Linux System Monitoring Tools Every SysAdmin Should Know

如果是centos7，请先yum install -y epel-release，然后yum install -y tool-name

 

Need to monitor Linux server performance? Try these built-in commands and a few add-on tools. Most distributions come with tons of Linux monitoring tools. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most fundamental commands when it comes to system analysis and debugging Linux server issues such as:

1. Finding out system bottlenecks
2. Disk (storage) bottlenecks
3. CPU and memory bottlenecks
4. Network bottleneck.

 

1. top – Process activity monitoring command

top command display Linux processes. It provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

Fig.01: Linux top command

Commonly Used Hot Keys With top Linux monitoring tools

Here is a list of useful hot keys:

Hot Key	Usage
t	Displays summary information off and on.
m	Displays memory information off and on.
A	Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f	Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o	Enables you to interactively select the ordering within top.
r	Issues renice command.
k	Issues kill command.
z	Turn on or off color/mono

How do I Find Out Linux CPU Utilization?

2. vmstat – Virtual memory statistics

The vmstat command reports information about processes, memory, paging, block IO, traps, and cpu activity.
# vmstat 3
Sample Outputs:

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 2540988 522188 5130400    0    0     2    32    4    2  4  1 96  0  0
 1  0      0 2540988 522188 5130400    0    0     0   720 1199  665  1  0 99  0  0
 0  0      0 2540956 522188 5130400    0    0     0     0 1151 1569  4  1 95  0  0
 0  0      0 2540956 522188 5130500    0    0     0     6 1117  439  1  0 99  0  0
 0  0      0 2540940 522188 5130512    0    0     0   536 1189  932  1  0 98  0  0
 0  0      0 2538444 522188 5130588    0    0     0     0 1187 1417  4  1 96  0  0
 0  0      0 2490060 522188 5130640    0    0     0    18 1253 1123  5  1 94  0  0

Display Memory Utilization Slabinfo

# vmstat -m

Get Information About Active / Inactive Memory Pages

# vmstat -a
How do I find out Linux Resource utilization to detect system bottlenecks?

3. w – Find out who is logged on and what they are doing

w command displays information about the users currently on the machine, and their processes.
# w username
# w vivek
Sample Outputs:

 17:58:47 up 5 days, 20:28,  2 users,  load average: 0.36, 0.26, 0.24
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
root     pts/0    10.1.3.145       14:55    5.00s  0.04s  0.02s vim /etc/resolv.conf
root     pts/1    10.1.3.145       17:43    0.00s  0.03s  0.00s w

4. uptime – Tell how long the Linux system has been running

uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.
# uptime
Output:

 18:02:41 up 41 days, 23:42,  1 user,  load average: 0.00, 0.00, 0.00

1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 – 3 and SMP systems 6-10 load value might be acceptable.

5. ps – Displays the Linux processes

ps command will report a snapshot of the current processes. To select all processes use the -A or -e option:
# ps -A
Sample Outputs:

  PID TTY          TIME CMD
    1 ?        00:00:02 init
    2 ?        00:00:02 migration/0
    3 ?        00:00:01 ksoftirqd/0
    4 ?        00:00:00 watchdog/0
    5 ?        00:00:00 migration/1
    6 ?        00:00:15 ksoftirqd/1
....
.....
 4881 ?        00:53:28 java
 4885 tty1     00:00:00 mingetty
 4886 tty2     00:00:00 mingetty
 4887 tty3     00:00:00 mingetty
 4888 tty4     00:00:00 mingetty
 4891 tty5     00:00:00 mingetty
 4892 tty6     00:00:00 mingetty
 4893 ttyS1    00:00:00 agetty
12853 ?        00:00:00 cifsoplockd
12854 ?        00:00:00 cifsdnotifyd
14231 ?        00:10:34 lighttpd
14232 ?        00:00:00 php-cgi
54981 pts/0    00:00:00 vim
55465 ?        00:00:00 php-cgi
55546 ?        00:00:00 bind9-snmp-stat
55704 pts/1    00:00:00 ps

ps is just like top but provides more information.

Show Long Format Output

# ps -Al
To turn on extra full mode (it will show command line arguments passed to process):
# ps -AlF

Display Threads ( LWP and NLWP)

# ps -AlFH

Watch Threads After Processes

# ps -AlLm

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