awk Regular expressions and the use of built-in functions examples of methods _linux shell

awk regular Expressions and built-in function examples are detailed:

1, Fuzzy matching:

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awk ' {if ($3~/97/) print $} ' DATA.F: Print the line if "97" is included in the third item
awk ' {if ($4!~/ufcx/) print $} ' DATA.F: Print if UFCX is not included in the third item

2. Exact match:

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awk ' {if ($5==66) print $} ' DATA.F: Print if item fifth is 66
awk ' {if ($5!=66) print $} ' DATA.F: Print if item fifth is not 66
awk ' {if ($1>$5) print $} ' DATA.F: Print If the first item is greater than item fifth

3, Case matching:

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If the awk ' {if (/[ss]ept/) print $} ' DATA.F: Compliant, print one line.
awk '/[ss]ept/{print $} ' DATA.F: Compliant, print the second field

4, any match:

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awk ' {if ($ ~/^.e/) print $} ' DATA.F: In the second field, the second character is E, the output
awk ' {if ($ ~/(LPS|FCX)/) print $} ' DATA.F: Fourth field contains LPs or FCX output

5, &&,| | ：

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awk ' {if ($ ~/1993/&& $2== ' Sept ') print $ ' DATA.F: Both sides are true output
awk ' {if ($ ~/a9/| | $2== ' Sept ') print $} ' DATA.F: One side for true output

6. Variable definition:

awk ' {date=$2;price=$5. if (date ~/[ss]ept/) print ' price ' = ' DATA.F: A variable definition that satisfies the price output of date Sept or Sept.

7, modify the value (the source file value does not change)

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awk ' {baseline=42; if ($1>baseline) $5=$5+100 print $} ' DATA.F: Three lines of procedure to ";" Segmentation

If you are modifying a text field, add "". For example: awk ' {if ($2== "may") $2= "TT"; print $} ' DATA.F

Above all show all data, awk ' {if ($2== ' may ') {$2= ' TT '; print $} ' DATA.F This only shows modified data, look carefully, in fact the syntax is the same as C, except that you have added a {} symbol at the very outset.

8, create a new domain: (source file values unchanged)

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awk ' {if ($5>$1) {$8=$5-$1;print $1,$8}} ' DATA.F:

Or awk ' {if ($5>$1) {Diff=$5-$1;print $1,diff}} ' DATA.F

9, Data statistics:

awk ' {(total+=$5)}end{print total} ' data.f: ' {(total+=$5)} ' and ' {print total} ' represent two different pieces of code, and if there is no cumulative result for each of the end output, End can be understood as the flag of the code paragraph, so that only the final result, the {print total}, is executed only once.

10, Statistics File size:

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Ls–l | awk ' {if (/^[^d]/) total=+$5}end{print total KB: ' Total} ':/^[^d]/header matching can not write field values

11. awk Built-in variables:

Number of ARGC command line arguments

ARGV Command line parameter arrangement

The use of system environment variables in ENVIRON support queues

FileName awk Browse file name

Number of records FNR browsing files

FS Set input field separator, equivalent to command line-f option

NF Browse record number of fields

The number of records that NR has read

OFS Output Field Separator

ORS Output Record Separator

RS Control Record Separator

12. awk built-in String handler function

Gsub (R, s) replaces R with s in whole $

Gsub (R, S, T) replaces R with S in the whole t

Index (s, t) returns the first position of the string T in S

Length (s) returns s

Match (S, R) tests if s contains a string that matches R, return position

Split (S, A, FS) on FS will be divided into sequence a

Sprint (f M T, exp) returns exp after format F m t

Sub (R, S, $) $ s replaces the position where the first R appears

SUBSTR (S, p) returns the suffix portion of the string s that starts with P

SUBSTR (S, p, n) returns the suffix portion of the string s starting with the length n from p

13. awk ' Gsub (/6\./,78) {print $} ' DATA.F: All "6." Replace with 78 and output

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awk ' {if ($2== "Sept") {sub (/3/, "9″,$0); print $}} ' DATA.F: Replace only the first occurrence of the

awk ' begin{print index ("Hello", "Lo")} ': Output value is 4

awk ' {if ($3== "3bc1997″) print length ($)" "$}" data.f

awk ' Begin{print match ("ABCD", "B")} ': Output 2

awk ' Begin{print match ("ABCD",/b/)} ': '//' and ' ' effect is the same

awk ' BEGIN {print split (' 123#234#654″, myarray, ' # ')} ': Returns the number of array elements, 123#234#654 is a string, and takes "#" as the delimiter, putting the string into an array.

awk ' {if ($1==34) print substr ($3,2,7)} ' DATA.F

awk ' Begin{print substr ("Helloleeboy", 2,7)} ': Output ellole

awk ' Begin{print substr ("Helloleeboy", 2,7)} ' DATA.F: output n times ellole,n number of rows DATA.F

14. awk ' Begin{print ' May\tday\n\nmay \104\141\171″} ': \104\141\171 represents day. \t:tab key, \ n: NewLine, \ddd: Octal

15, echo "65" | awk ' {printf '%c\n ', $} ': printf function, similar to C, output to a. (ASCII code)

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echo "65" | awk ' {printf '%d\n ', $} ': output 65 digits.

awk ' {printf '%-15s%s\n ', $2,$3} ' data.f: '%-15s ' left-aligned 15-character length

awk ' {if (age<$1) print $} ' age=80 data.f and awk ' {age=49;if (age<$1) print $} ' data.f as a result, the former passes the value into awk, which defines a variable in awk.