Shell scripts to monitor Linux system load vs. CPU, memory, hard disk, number of users

Main contents of this section:
Use Shell script to monitor Linux system load, CPU, memory, hard disk, user logins.

First, the Linux system alarm mail script

# vim /scripts/sys-warning.sh
#! / bin / bash
#site: www.jquerycn.cn
#Monitor the system load and CPU, memory, hard disk, and the number of logged-in users. If the alert value is exceeded, an email alert will be sent.
 
#Extract the IP address information of this server
IP = `ifconfig eth0 | grep" inet addr "| cut -f 2 -d": "| cut -f 1 -d" "`
 
# 1. Monitor the change of system load and send an email alert when it exceeds:
 
#Grab the total number of CPUs
cpu_num = `grep -c‘ model name ’/ proc / cpuinfo`
 
#Grab the average load value of the current system for 15 minutes
load_15 = `uptime | awk‘ {print $ 12} ’`
 
#Calculate the average load value of a single core of the current system for 15 minutes. If the result is less than 1.0, the previous single digits are filled with 0.
average_load = `echo" scale = 2; a = $ load_15 / $ cpu_num; if (length (a) == scale (a)) print 0; print a "| bc`
 
#Take the single-digit integer of the above average load value
average_int = `echo $ average_load | cut -f 1 -d". "`
 
#Set the 15-minute average load alarm value of a single core of the system to 0.70 (that is, the alarm is used when more than 70% is used).
load_warn = 0.70
 
#When the average load value of a single core for 15 minutes is greater than or equal to 1.0 (that is, the single-digit integer is greater than 0), send an email alert directly; if it is less than 1.0, perform a second comparison
if (($ average_int> 0)); then
echo "The average load of the $ IP server for 15 minutes is $ average_load, which exceeds the alert value of 1.0, please handle it immediately!" | mutt -s "$ IP server system load severe alarm !!!" [email protected]
else
 
#Compare the current 15-minute average load value with the alarm value (it will return 1 when it is greater than 0.70, and 0 if it is less than)
load_now = `expr $ average_load \> $ load_warn`
 
#If the 15-minute average load of a single core of the system is greater than the alarm value of 0.70 (return value is 1), send an email to the administrator
if (($ load_now == 1)); then
echo "The average load of the $ IP server in 15 minutes reaches $ average_load, which exceeds the alert value of 0.70, please handle it in time." | mutt -s "$ IP server system load alarm" [email protected]
fi
 
fi
 
# 2. Monitor the CPU status of the system and send an alert email when the usage exceeds 80%:
 
#Take the current idle CPU percentage ratio (take only the integer part)
cpu_idle = `top -b -n 1 | grep Cpu | awk‘ {print $ 5} ‘| cut -f 1 -d". "`
 
#Set the alarm value of the idle CPU to 20%. If the current CPU usage exceeds 80% (that is, the remaining is less than 20%), an email alert will be sent immediately.
if (($ cpu_idle <20)); then
echo "The remaining $ cpu_idle% of the $ IP server cpu, the usage rate has exceeded 80%, please handle it in time." | mutt -s "$ IP server CPU alarm" [email protected]
fi
 
# 3. Monitor the swap of the system swap partition, and send an alert email when the usage exceeds 80%:
 
#Total allocation of swap partitions allocated by the system
swap_total = `free -m | grep Swap | awk‘ {print $ 2} ’`
 
#Current remaining swap partition free size
swap_free = `free -m | grep Swap | awk‘ {print $ 4} ’`
 
#Currently used swap partition used size
swap_used = `free -m | grep Swap | awk‘ {print $ 3} ’`
 
if (($ swap_used! = 0)); then
#If the swap partition has been used, calculate the percentage of the total remaining swap partition free, expressed as a decimal, and you must add an integer 0 before the decimal point
swap_per = 0`echo "scale = 2; $ swap_free / $ swap_total" | bc`
 
#Set the alarm value of the swap partition to 20% (that is, when the usage exceeds 80%).
swap_warn = 0.20
 
#The current remaining swap partition percentage is compared with the alarm value (when it is greater than the alarm value (that is, the remaining 20% or more) it will return 1 and when it is less (that is, the remaining is less than 20%) it will return 0)
swap_now = `expr $ swap_per \> $ swap_warn`
 
#If the current swap partition usage exceeds 80% (that is, the remaining is less than 20%, the return value above is equal to 0), send an email alert immediately
if (($ swap_now == 0)); then
echo "Only $ swap_free M of the $ IP server swap partition is left unused, the remaining is less than 20%, and the usage has exceeded 80%, please handle it in time." | mutt -s "$ IP server memory alarm" [email protected]
fi
 
fi
 
# 4. Monitor the usage of the system hard disk root partition and send an alert email when the usage exceeds 80%:
 
#Take the used percentage value of the current root partition (/ dev / sda3) (take only the integer part)
disk_sda3 = `df -h | grep / dev / sda3 | awk‘ {print $ 5} ‘| cut -f 1 -d"% "`
 
#Set the alert value of the free hard disk capacity to 80%. If the current hard disk usage exceeds 80%, send an email alert immediately.
if (($ disk_sda3> 80)); then
echo "The usage of $ IP server / root partition has exceeded 80%, please handle it in time." | mutt -s "$ IP server hard disk alarm" [email protected]
fi
 
# 5. Monitor the user login status of the system, and send an alert email when the number of users exceeds 3:
 
#Take the current user login number (take only the value part)
users = `uptime | awk‘ {print $ 6} ’`
 
#Set the alarm value for the number of login users to 3. If the current number of users exceeds 3, send an email alert immediately
if (($ users> = 3)); then
echo "The number of $ IP server users has reached $ users, please handle it in time." | mutt -s "Alarm of $ IP server users" [email protected]
fi
# chmod a + x /scripts/sys-warning.sh
Second, join the task plan: Detect every ten minutes, send an email immediately if there is an alarm (once every ten minutes).

# crontab -e
* / 10 * * * * /scripts/sys-warning.sh
# service crond restart
Third, start the Sendmail service or install the mail client msmtp software under linux (a tool similar to foxmail)
1. Download and install: http://downloads.sourceforge.net/msmtp/msmtp-1.4.16.tar.bz2?modtime=1217206451&big_mirror=0
 

# tar jxvf msmtp-1.4.16.tar.bz2
# cd msmtp-1.4.16
# ./configure --prefix = / usr / local / msmtp
# make
# make install
2. Create msmtp configuration file and log file (host is the mail domain name, mail user name test, password 123456)

# vim ~ / .msmtprc
account default
host 126.com
from [email protected]
auth login
user test
password 123456
logfile ~ / .msmtp.log
# chmod 600 ~ / .msmtprc
# touch ~ / .msmtp.log
3, Mutt installation configuration: (Generally there is a default installation of Mutt under Linux)

set sendmail = "/ usr / local / msmtp / bin / msmtp"
set use_from = yes
set realname = "memory"
set from = [email protected]
set envelope_from = yes
set rfc2047_parameters = yes
set charset = "utf-8"
4. Email sending test (-s email header)

# echo "Email content 123456" | mutt -s "Email header test message" [email protected]
 

Shell script to monitor Linux system load and CPU, memory, hard disk, and number of users