1. Delete 0-byte files
find -type f -size 0 -exec rm -rf {} \; `Copy the code2. View processes in order of memory
PS -e -o "%C : %p : %z : %a"|sort -k5 -nr
Copy the code3, in order of CPU utilization
ps -e -o "%C : %p : %z : %a"|sort -nr
Copy the code4. Print the CACHE URL
grep -r -a jpg /data/cache/* | strings | grep "http:" | awk -F'http:' '{print "http:"$2; } 'Copy the codeQuery the number of concurrent HTTP requests and their TCP connection status:
netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
Copy the codeSed -i ‘/root/s /no/yes/’ /etc/ssh/sshd_config sed -i’ /root/s /no/yes/’ /etc/ssh/sshd_config sed
How to kill the MySQL process
Ps aux | grep mysql | grep -v grep | awk '{print $2}' | xargs kill 9 (learn to awk utility) killall - TERM mysqld kill 9 ` cat / usr/local/apache2 / logs/HTTPD pid ` try killing process pidCopy the codeRun level 3 enabled services:
Ls/etc/rc3. D/S * | the cut - c - 15 (see to the purpose of the cut, interception of data)Copy the code9. How to display multiple messages in a SHELL using EOF
cat << EOF
+--------------------------------------------------------------+
| === Welcome to Tunoff services === |
+--------------------------------------------------------------+
EOF
Copy the codeMySQL > create soft link for MySQL > create soft link for MySQL
cd /usr/local/mysql/bin
for i in *
do ln /usr/local/mysql/bin/$i /usr/bin/$i
done
Copy the code11. Obtain the IP address
The ifconfig eth0 | grep "inet addr:" | awk '{print $2}' | the cut - 6 - c or ifconfig | grep 'inet addr:' | grep -v '127.0.0.1' | the cut -d: -f2 | awk '{ print $1}'Copy the code12, memory size:
free -m |grep "Mem" | awk '{print $2}'
Copy the code13
netstat -an -t | grep ":80" | grep ESTABLISHED | awk '{printf "%s %s\n",$5,$6}' | sort
Copy the codeQuery the number of concurrent Apache requests and their TCP connection status:
netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
Copy the code15, because the colleague wants to count the size of all the JPG files below the server, wrote a SHELL to him to count. Originally implemented with XARgs, but it handles one part at a time. There are multiple summations… The following command will solve the problem.
find / -name *.jpg -exec wc -c {} \; |awk '{print $1}'|awk '{a+=$1}END{print a}'Copy the codeMore than the number of cpus (accounting multiple cpus, the cat/proc/cpuinfo | grep -c processor), the more the lower the system load, can deal with is, the more the number of requests per second.
16. CPU load
cat /proc/loadavg
Copy the codeCheck if the first three output values exceed 4 times the system logical CPU.
17. CPU load
mpstat 1 1
Copy the codeCheck whether %idle is too low (e.g., less than 5%).
18. Memory space
free
Copy the codeTo check if free is too low, you can also use # cat /proc/meminfo
19. SWAP space
free
Copy the codeCheck whether the swap used value is too high. If the swap used value is too high, check whether the swap action is frequent.
vmstat 1 5
Copy the codeObserve whether the SI and SO values are large
20. Disk space
df -h
Copy the codeCheck whether the Use% of a partition is too high (for example, over 90%). If the space of a partition is nearly used up, go to the mount point of the partition and run the following command to find the files or directories that occupy the most space:
du -cks * | sort -rn | head -n 10
Copy the code21. Disk I/O load
iostat -x 1 2
Copy the codeCheck whether the I/O usage (%util) exceeds 100%
22. Network load
sar -n DEV
Copy the codeCheck whether the network traffic (RXBYT /s, TXBYT /s) is too high
23. Network error
netstat -i
Copy the codeCheck for network errors (drop FIFo colls carrier) by using the # cat /proc/net/dev command
24. Number of network connections
Netstat - an | grep -e "^" (TCP) | the cut - 68 - c | sort | uniq -c | sort - nCopy the code25. Total number of processes
ps aux | wc -l
Copy the codeCheck whether the number of processes is normal (for example, more than 250)
26. Number of runnable processes
vmwtat 1 5
Copy the codeColumn gives the number of runnable processes, checking to see if they exceed 4 times the system logical CPU
27, processes,
top -id 1
Copy the codeObserve for abnormal processes.
28, network status, check whether DNS, gateway and other normal connectivity
29, user
who | wc -l
Copy the codeYou can also check if there are too many logins (say more than 50) using the command # uptime.
30. System logs
# cat /var/log/rflogview/*errors
Copy the codeCheck for exception errors. You can also search for exception keywords, such as:
grep -i error /var/log/messages
grep -i fail /var/log/messages
Copy the code31. Core logs
dmesg
Copy the codeCheck whether abnormal errors are recorded.
32. System time
date
Copy the codeCheck whether the system time is correct.
33. Number of open files
lsof | wc -l
Copy the codeCheck whether the total number of open files is too large.
34, logs,
# logwatch - printCopy the codeConfigure /etc/log.d/logwatch.conf, set Mailto to your email address, and start the mail service (sendmail or postfix) so that you can receive log reports every day. By default, logwatch reports only yesterday’s logs. You can use # logwatch — print — range all to get all log analysis results. You can use # logwatch — print — detail high to get more specific log analysis results (rather than just error logs). 35. Kill the processes associated with port 80
Lsof - I: 80 | grep -v "ID" | awk '{print "kill 9", $2}' | shCopy the codeClear dead processes
ps -eal | awk '{ if ($2 == "Z") {print $4}}' | kill -9
Copy the codeTcpdump packet capture is used to prevent port 80 from being attacked and analyze data
tcpdump -c 10000 -i eth0 -n dst port 80 > /root/pkts
Copy the code38, Then check the number of IP repeats and sort them from smallest to largest. Note that “-t\ +0” is separated by two Spaces
# less pkts | awk {'printf $3"\n"'} | cut -d. -f 1-4 | sort | uniq -c | awk {'printf $1" "$2"\n"'} | sort -n -t\ +0
Copy the codeCheck how many active PHP-CGI processes there are
netstat -anp | grep php-cgi | grep ^tcp | wc -l
Copy the code40. View the automatic startup service
chkconfig --list | awk '{if ($5=="3:on") print $1}'
Copy the code41. Kudzu Check the NIC model
kudzu --probe --class=network
Copy the codeCommon regular expressions
[u4e00-u9fa5] [u4e00-u9fa5]
Note: Matching Chinese is really a headache, with this expression is easy to do
2. Match double-byte characters (including Chinese characters) : 1
Note: Can be used to calculate the length of a string (2 for a double-byte character, 1 for ASCII characters)
3. Regular expressions that match blank lines: \n\s*\r
Comment: Can be used to delete blank lines
4. Regular expressions that match HTML tags: <(\S
?). 2
>.
? < 1 > / \ | <.
? />
Note: The version circulating on the Internet is so bad that this one only matches parts and is still useless for complex nested tags
5. Regular expression that matches the first and last whitespace characters: ^\s
|\s
$
Comment: a useful expression that can be used to remove whitespace (including Spaces, tabs, page feeds, and so on) at the beginning and end of a line
6. Regular expressions matching Email addresses:
\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*
Copy the codeNote: Useful for form validation
[A-za-z]+://3*
Comments: the version circulating on the Internet is very limited in function, the above one can basically meet the needs
8. Check whether the matching account is valid (starting with a letter, allowing 5-16 bytes, alphanumeric underscores) :
^ [a zA - Z] [a - zA - Z0-9 _] {4, 15} $Copy the codeNote: Useful for form validation
9. Match the domestic telephone number: \ d {3} – \ d {8} | \ d {4} – \ d {7}
Comments: The matching form is 0511-4405222 or 021-87888822
10. Match Tencent QQ id: 1-9{4,}
Comments: Tencent QQ number starts from 10000
11. Match Chinese zip code: [1-9]\d{5}(? ! \d)
Note: China postcodes are 6 digits
12. The matching XXX: \ d {15} | \ d {and}
Comments: Chinese ××× is the 15th or 18th place
13. Match the IP address: \d+.\d+.\d+
Note: It is useful for extracting IP addresses
14. Match a specific number:
^[1-9]\d*$// Matches positive integer ^-[1-9]\d*$// Matches negative integer ^-? \ [1-9] d * $^ / / matching integer \ [1-9] d * | 0 $/ / match non-negative integer (positive integer + 0) ^ - [1-9] \ | 0 $d * / / match the positive integer (negative integers + 0) ^ 1 - [9] \ d * \ \ d * \ | 0. [1-9] \ d \ d * * $/ / match is floating point ^ - (1-9] [\ d * \ \ d * \ | 0. [1-9] \ d \ d * *) $/ / take floating-point ^ - match? ([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0? \. | 0 + 0) $/ / match floating-point ^ [1-9] \ d * \ \ d * \ | 0. [1-9] \ d \ d * * | 0? \. | 0 0 + $/ / match nonnegative floating-point Numbers (is floating point number + 0) ^ (- (1-9] [\ d * \ \ d * \ | 0. [1-9] \ d \ d * *)) | 0? \. | 0 0 + $/ / match is a floating point number (negative floating-point number + 0)Copy the codeComments: useful when dealing with a large amount of data, pay attention to the revision of specific applications
15. Match a specific string:
^[A-za-z]+$// Matches A string of 26 letters ^[A-z]+$// Matches A string of 26 letters in upper case ^[A-z]+$// Matches A string of 26 letters in lower case ^[A-zA-z0-9]+$// Matches A string consisting of digits and 26 letters. ^\w+$// Matches A string consisting of digits, 26 letters, or underscoresCopy the codeComments: Some of the most basic and commonly used expressions
