12. sed command and regular expression

awk command

To intercept a segment in a document

#awk-F ': ' {print$1} 1.txt prints the first paragraph

#awk-F ': ' ofs= ' # ' {print$1,$2,$3,$4} 1.txt specifies the delimiter to display the result as #, or you can use a custom character to concatenate each segment {print$1 "#"

Match character or string

#awk '/root/' 1.txt

Match for a segment

#awk-F ': ' $ ~/oo/' 1.txt

Multiple matches

#awk-F ': '/root/{print $1,$3};$1~/test/;$3~/20/' 1.txt

Change the value of a segment

#awk-F ': ' $1= ' root ' 1.txt

Number calculation, add the third and fourth values, and give the seventh paragraph

#awk-F ' {ofs= ': '} {$7=$3+$4;print$0} ' 1.txt

Calculate the sum of the third paragraph

#awk-F ': ' {(tot=tot+$3)}; End{print tot} ' 1.txt

if keyword

#awk-F ': ' {if ($1== "root") print$0} ' 1.txt

Built-in variable NF number, NR line number '

Print lines after 20 lines

#awk ' nr>20 ' 1.txt

Print 20 lines later and the first paragraph contains ' SSH ' lines

#awk-F ': ' nr>20 && $1~/ssh/' 1.txt

Conditional operator <,>,==,!=,>=,<=

The third paragraph is 0

#awk-F ': ' $3== ' 0 "' 1.txt

The third paragraph is greater than or equal to 500

#awk-F ': ' $3>=500 ' 1.txt

Description, and so on when comparing numbers, cannot add double quotes, if written $3>= "500" does not meet the requirements

The 7th paragraph is not '/sbin/nologin '

#awk-F ': ' $7!= '/sbin/nologin ' 1.txt

The third paragraph is less than the fourth paragraph

#awk-F ': ' $3<$4 ' 1.txt

The third segment is greater than 5 and less than 7

#awk-F ': ' $3>5 && $3<7 ' 1.txt

The third paragraph is greater than 5, or the 7th paragraph is '/bin/bash '

#awk-F ': ' $3> "5" | | $7== "/bin/bash" ' 1.txt

Extended
Using external shell variables in awk http://www.aminglinux.com/bbs/thread-199-1-1.html
awk merges a file http://www.aminglinux.com/bbs/thread-493-1-1.html
Concatenate a file multiple lines into a line http://www.aminglinux.com/bbs/thread-266-1-1.html
The use of Gsub functions in awk http://www.aminglinux.com/bbs/thread-200-1-1.html
awk intercepts specifying multiple fields as one row http://www.aminglinux.com/bbs/thread-224-1-1.html
Filter two or more keywords http://www.aminglinux.com/bbs/thread-198-1-1.html
Generate the following structure file with awk http://www.aminglinux.com/bbs/thread-5494-1-1.html
awk Tutorial Http://www.cnblogs.com/emanlee/p/3327576.html

awk Prints single quotation marks with print http://www.aminglinux.com/bbs/thread-1738-1-1.html

Merge two files http://www.aminglinux.com/bbs/thread-945-1-1.html

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12. sed command and regular expression