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Editor to share with you what are the practical commands of linux operation and maintenance, I believe most people do not know much about it, so share this article for your reference. I hope you will learn a lot after reading this article. Let's learn about it together.

1. Delete 0-byte file

The code is as follows:

Find-type f-size 0-exec rm-rf {}\

two。 View the process

Sort by memory from large to small

The code is as follows:

Ps-e-o "% C:% p:% z:% a" | sort-K5-nr

3. Ranked by cpu utilization from large to small

The code is as follows:

Ps-e-o "% C:% p:% z:% a" | sort-nr

4. Print the URL in cache.

The code is as follows:

Grep-r-a jpg / data/cache/* | strings | grep "http:" | awk-Fairfax https'{print "http:" $2;}'

5. Check the number of concurrent requests for http and their TCP connection status:

The code is as follows:

Netstat-n | awk'/ ^ tcp/ {+ + S [$NF]} END {for (an in S) print a, S [a]}'

6. Sed-I'/ Root/s/no/yes/' / etc/ssh/sshd_config sed in this text, one line of Root matches the line of Root and replaces no with yes.

7. How to kill the mysql process:

The code is as follows:

Ps aux | grep mysql | grep-v grep | awk'{print $2}'| xargs kill-9 (learn the purpose of awk)

Killall-TERM mysqld

Kill-9 `cat / usr/local/apache2/logs/ httpd.pid` try the killing process PID

8. Displays running services enabled at level 3:

The code is as follows:

Ls / etc/rc3.d/S* | cut-c 15-(learn the purpose of cut and intercept data)

9. How to display multiple messages when writing SHELL, using EOF

The code is as follows:

Cat / root/pkts

thirty-nine。 Then check the repetition number of IP and sort it from smallest to largest. Notice that there are two spaces in the middle of "- t\ + 0".

The code is as follows:

# less pkts | awk {'printf $3 "\ n"'} | cut-d. -f 1-4 | sort | uniq-c | awk {'printf $1 "" $2 "\ n"'} | sort-n-t\ + 0

forty。 Check how many php-cgi processes are active

The code is as follows:

Netstat-anp | grep php-cgi | grep ^ tcp | wc-l

Chkconfig-- list | awk'{if ($5mm = "3:on") print $1}'

41.kudzu to check the network card model

The code is as follows:

Kudzu-probe-class=network

forty-two。 Common regular expressions

Regular expressions that match Chinese characters: [\ u4e00 -\ u9fa5]

Note: matching Chinese is really a headache. It's easy to have this expression.

Match double-byte characters (including Chinese characters): [^\ X00 -\ xff]

Note: can be used to calculate the length of a string (a double-byte character length meter 2 ~ ~ ASCII character counter 1)

A regular expression that matches a blank line:\ n\ s*\ r

Comment: can be used to delete blank lines

Regular expression that matches the HTML tag:] * >. *? |

Commentary: the version circulated on the Internet is too bad, the above one can only match part of it, and there is still nothing I can do about complex nested tags.

Regular expression that matches the leading and trailing white space characters: ^\ s* |\ sblank $

Comment: a very useful expression that can be used to delete white space characters (including spaces, tabs, page feeds, etc.) at the beginning and end of a line

The regular expression that matches the Email address:\ W + ([- +.]\ w +) * @\ w + ([-.]\ w +) *.\ w + ([-.]\ w +) *

Comment: form validation is very useful

Regular expression that matches the URL URL: [a-zA-z] +: / / [^\ s] *

Note: the function of the version circulated on the Internet is very limited, and the above version can basically meet the needs.

Whether the matching account is legal (5-16 bytes are allowed at the beginning of the letter, and alphanumeric underscores are allowed): ^ [a-zA-Z] [a-zA-Z0-9 _] {4j 15} $

Comment: form validation is very useful

Match domestic phone number:\ d {3} -\ d {8} |\ d {4} -\ d {7}

Commentary: matching forms such as 0511-4405222 or 021-87888822

Match Tencent QQ number: [1-9] [0-9] {4,}

Commentary: Tencent QQ starts from 10000

Match the postcode of China: [1-9]\ d {5} (?!\ d)

Commentary: the postal code of China is 6 digits

Match ID:\ d {15} |\ d {18}

Commentary: Chinese ID cards are 15 or 18 digits

Match ip address:\ d +\.\ d +\.\ d +

Note: useful when extracting ip addresses

Match specific numbers:

The code is as follows:

^ [1-9]\ positive integer matching $/ /

^-[1-9]\ negative integer matching $/ /

^ -? [1-9]\ match integer

^ [1-9]\ d* | 0 $/ / matches a non-negative integer (positive integer + 0)

^-[1-9]\ d* | 0 $/ / matches non-positive integers (negative integers + 0)

^ [1-9]\ d *\.\ d * | 0\.\ d * [1-9]\ dfloat $/ / matches positive floating point numbers

^-([1-9]\ d *.\ d * | 0.\ d * [1-9]\ d *) $/ / matches negative floating point numbers

^ -? ([1-9]\ d *.\ d * | 0\.\ d * [1-9]\ d * | 0?\ .0 + | 0) $/ / match floating point number

^ [1-9]\ d *.\ d * | 0\.\ d * [1-9]\ d * | 0?\ .0 + | 0 $/ / matches non-negative floating point numbers (positive floating point number + 0)

^ (- ([1-9]\ d *\.\ d * | 0\.\ d * [1-9]\ d *)) | 0?\ .0 + | 0 $/ / matches non-positive floating point numbers (negative floating point + 0)

Commentary: useful when dealing with a large amount of data, pay attention to corrections in specific applications

Match a specific string:

The code is as follows:

^ [A-Za-z] + $/ / matches a string of 26 English letters

^ [Amurz] + $/ / matches a string of 26 English letters in uppercase

^ [amurz] + $/ / matches a string of 26 lowercase letters

^ [A-Za-z0-9] + $/ / matches a string of numbers and 26 letters

^\ w match $/ / match a string consisting of numbers, 26 letters, or underscores

These are all the contents of this article entitled "what are the practical commands for linux operation and maintenance?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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