Alfred Aho Brian Kernighan Peter Weinberger gawk awk GUN. GNU linux. gawk

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1 awk linux/unix awk linux/unix ( ) awk Alfred AhoBrian KernighanPeter Weinbergergawk awk GUN awk gawk GNU linux Bell awk GNU awk gawk awk [options] 'script' var=value file(s) awk [options] -f scriptfile var=value file(s) fs -F: awk nnn -mf Bell awk nnn -mr awk

2 awk gawk awk awk awk unix unix \x func fs ****= ^^=fflush (grep Posix ) [[:alpha:]] program-text -f bug pattern {action $ awk '/root/' test$ awk '$3 < 100' test action action

3 3 RS / / $2>%1 ~( )~!( ) BEGIN END BEGIN END! " #%$" #& -. +, *!"# / * :9<;!"$%& / !") B C / * #*%)+, 3 " D EF 'GH I)J -./( 0%)$!*% K L M N OP 3 0!!%* Q R S! T UV W * XY * $01&$&,2 " #)Z\[ ]^ '_<`@F a ')( (* $10% b * ')()* '= >@? A (*

4 F %! c %!$d e f g 78 * i j " # ')(\h 'GH `@F $"%*!0# 0 k l J\m%$on@p 1 q<r@s t u % 6 " # 3 * %! 3 * -x *+, 3 " 'GH I -x * " # ')(\h 'GH I -x *! ')(\h 'GH I vow!10%",2 y 3z * -./(* S!<`@F (* S! E 1 h (* " h { [ *! ')(\h 'GH S! E 1 h (* vow!,!, y 3z " h { S! ~ ')(\h 'GH I 678(* 9<; * < 9:;-<:: ƒ I => # 8 ^?? ˆ vow<š AAB n^ CCDDB T@Œ A h `@F Ž 9 $ :;@ $ 9B S $ <::: 99 ˆ š$ " #šœo_ < 3 )vow<š n^ J ˆ R awk ORS RS

5 $0 $ awk '{print $0' test test NR NR 1$ awk '{print NR,$0' test test NF tab awk $ awk '{print $1,$3' test test () FS tab -F FS $ awk -F: '{print $1,$5' test $awk -F'[:\t]' '{print $1,$3' test tab OFS OFS$ awk -F: '{print $1,$5' test$1$5 unix Sed Grep gawk awk 6E 64 6C 6D 6

6 6 6F 6G Grep $ awk '$1 ~/^root/' root test test conditional expression1? expression2: expression3 $ awk '{max = {$1 > $3? $1: $3: print max' test $1 max $3 max $ awk '$1 + $2 < 100' test 100 $ awk '$1 > 5 && $2 < 10' test, 5 10 $ awk '/root/,/mysql/' mysql test root

7 $ cat /etc/passwd awk -F: '\ NF!= 7{\ printf("line %d,does not have 7 fields:%s\n",nr,$0)\ $1!~ /[A-Za-z0-9]/{printf("line %d,non alpha and numeric user id:%d: %s\n,nr,$0)\ $2 == "*" {printf("line %d, no password: %s\n",nr,$0)' cat awkawk (NF) 7 printf "line?? does not have 7 fields" printf no alpha and numeric user id" no passwd $ awk '/^(no so)/' test----- no so $ awk '/^[ns]/{print $1' test----- n s $ awk '$1 ~/[0-9][0-9]$/(print $1' test----- $ awk '$1 == 100 $2 < 50' test $ awk '$1!= 10' test $ awk '/test/{print $1 + 10' test----- test 10 $ awk '{print ($1 > 5? "ok "$1: "error"$1)' test $ awk '/^root/,/^mysql/' test---- root mysql mysql root

8 awk Variable = expression$ awk '$1 ~/test/{count = $2 + $3; print count' test,,awk count test 4 awkscript month=4 year= awk test month year test BEGIN $ awk '{$2 = + $1; print ' awk 100$1 $2 test, $2 $ awk '$1 == "root"{$1 ="test";print' root test test mary!"# BEGIN awk OFS, RS FS $ awk 'BEGIN{FS=":"; OFS="\t"; ORS="\n\n"{print $1,$2,$3 (FS) (OFS) test (ORS) $ awk 'BEGIN{print "TITLE TEST"!#$ END $ awk 'END{print "The number of records is" NR' test awk awk $ awk -F: -f $ awk -F: '{IGNORECASE=1; $1 == "MARY"{print NR,$1,$2,$NF'test IGNORECASE 1 awk shell $ awk '$1 = 100 {print $1 > "output_file" ' test 100 output_file >> getline getline NF,NR 0 FNR getline -1 1

9 $ awk 'BEGIN{ "date" getline d; print d' getline test d linux date $ awk 'BEGIN{"date" d; split(d,mon); print mon[2]' getline getline test shell dsplit date d mon mon $ awk 'BEGIN{while( "ls" getline) getline ls print' ls geline BEGIN $ awk 'BEGIN{printf "What is your name?"; getline name < "/dev/tty" $1 ~name {print "Found" name on line NR "." END{print "See you," name "." test What is your name?", name getline name print END See you name $ awk 'BEGIN{while (getline < "/etc/passwd" > 0) lc++; print /etc/passwd lc lc'awk lc 1 getline -1 0 while (getline < -1 "/etc/passwd") awk close() $ awk '{print $1, $2 "sort" ' test END linux sort,end {close("sort")awd print system awk linux$ awk 'BEGIN{system("clear")' fflush fflush(""), awk C %& ž Ÿ {if (expression){ statement; statement;... $ awk '{if ($1 <$2) print $2 "too high"' test

10 $ awk '{if ($1 < $2) {count++; print "ok"' ok test. count %&' ž Ÿ {if (expression){ statement; statement;... else{ statement; statement;... $ awk '{if ($1 > 100) print $1 "bad" ; else print "ok"' test $1 100 $1 bad, ok $1 count $1 %&'%& $ awk '{if ($1 > 100){ count++; print $1 else {count--; print $2' test $1 100 count ž Ÿ {if (expression){ statement; statement;... else if (expression){ statement; statement;... else if (expression){ statement; statement;... else { statement; statement;... awk :while for special for $ awk '{ i = 1; while ( i <= NF ) { print NF,$i; i++' NF( ), i test 1 i 1 i NF. $ awk '{for (i = 1; i<nf; i++) print NF,$i' test breadkcontinue break continue {for ( x=3; x<=nf; x++) if ($x<0){print "Bottomed out!"; break {for ( x=3; x<=nf; x++)

11 3 if ($x==0){print "Get next item"; continue next awk {if ($1 ~/test/){next else {print exit awk END 0 awk $ awk {name[x++]=$2;end{for(i=0;i<nr;i++) print i,name[i]' test 1 name name xawk x END for special for {for (item in arrayname){ print arrayname[item] G;<;H )ö I%!JKLM0%&H' (H IJLLG * š I * * count["test"] for for (index_value in array) statement $1 :$ awk '{count[$1]++ END{for(name in count) print name,count[name]' count test delete $ awk '{line[x++]=$1 END{for(x in line) delete(line[x])' test line special for

12 sub sub (regular expression, substitution string): sub (regular expression, substitution string, target string) $ awk '{ sub(/test/, "mytest"); print ' testfile $ awk '{ sub(/test/, "mytest"); $1; print ' testfile gsub gsub sub gsub (regular expression, substitution string) gsub (regular expression, substitution string, target string) $ awk '{ gsub(/test/, "mytest"); print ' testfile $ awk '{ gsub(/test/, "mytest"), $1 ; print ' testfile test mytest mytest index 1 index(string, substring) $ awk '{ print index("test", "mytest") ' testfile test mytest 3 length

13 length( string ) length $ awk '{ print length( "test" ) ' $ awk '{ print length ' testfile test testfile substr 1 substr( string, starting position ) substr( string, starting position, length of string ) $ awk '{ print substr( "hello world", 7,11 ) ' world RLENGTH 0match RSTART substr match match( string, regular expression ) $ awk '{start=match("this is a test",/[a-z]+$/); print start' $ awk '{start=match("this is a test",/[a-z]+$/); print start, RSTART, RLENGTH ' 11 RSTART RLENGTH 11(start)11(RSTART) 4(RLENGTH) toupper tolower gawk toupper( string )

14 » µ» u u & ¼ ¼ F F t t ¼ ¼ tolower( string ) $ awk '{ print toupper("test"), tolower("test") ' split FS split( string, array, field separator ) split( string, array ) $ awk '{ split( "20:18:00", time, ":" ); print time[2] ' time 18 systime ( ) systime() $ awk '{ now = systime(); print now ' strftime C strftime systime( [format specification][,timestamp] ) ª «% ± ²³ <± - µ '( - µ -N ¹@b -4 ¹@b º5» - - ½ p ¾ +,<u@ '( +,<u@ %¼ µ '*( '*N (» -& µ O;P;QQ 9 À Á Â - µ $ k l S S!<`@F % -2 _ ½ p ¾ ^ Ã P8t % -$ _ ½ p ¾ ^ Ã KPt

15 Š Ý 9 ¼ Æ. -R = K ¹ K»ÅÄ SÆ6 - ½ -+ ½ p ¾ ^ Ã p ¾ ^ Ã ¹\È 'É - KPt ^ Ã ' +;5+( Ê - ½ p ¾ ^ Ã -3 ½ p ¾ ^ Ã SÆ6! µ ' µç - ½ p ¾ ^ Ã µ ' µç ( - ½ p ¾ ^ Ã SÆ6! µ ' µ S ; º5» - Ë Ì Í µ 'O;P;QQ( ; º%¼ -S Ë Ì Í & 'KP ( - Î 3 " ^ Ã -E )¹\È ¼Ï -T '5&,( -- Ð ' Ñ '-( 'QQ( Ç J S! µ J S! µ >@? ( >@? ( $ awk '{ now=strftime( "%D", systime() ); print now ' $ awk '{ now=strftime("%m/%d/%y"); print now ' ÒoÓ ÔÕ P'( Ù%Ú<Û '( Ý y 3 '( '( Þ, '( ßáà f 3 ö '( 3 '( Ö Ø Ü U'( â ã ä '( å æ '(y 3 '( Þ, $ç è é ê '( ë<ìs! s g í g î t g 3 awk function name ( parameter, parameter, parameter,... ) {

16 statements return expression # the return statement and expression are optional ()*+) awk '{printf("%s,",$1)' filename

17 AWK 0.awk 3 : 1.awk awknawk gawk gawk awk 2. awk 1) [opion] 'awk_script' input_file1 [input_file2...] awk option -F fs : IFS fs awk -f filename : filename awk_script -v var=value : awk_script 2) awk_script #!/bin/awk -f shell 3) awk_script : awk -f awk input_file(s) 3. awk 1) awk_script : NEWLINE awk_script awk_cmd awk_cmd awk_cmd awk : awk_pattern { actions awk_script awk_script 2) : awk ' BEGIN { actions awk_pattern1 { actions... awk_patternn { actions END { actions ' inputfile BEGIN { actions END { actions 3) awk awk : BEGIN awk actions ( $2 ) awk $0 1 shell $1 IFS 2 actions awk_cmd awk_pattern actions awk_cmd awk_cmdawk

18 awk awk END actions 4) iput_file awk 5) awk_cmd actions awk_pattern awk_cmd actions (print $0) awk_cmd awk_pattern actions 6) END BEGIN END BEGIN awk_script awk_script awk_script BEGIN { actions awk input_file awk 7) awk 8) awk awk 4.awk_pattern awk_pattern actions actionsawk_pattern : 1) awk_pattern: /regexp/ awk : \ ^ $. [] () * // regexp + : awk grep sed 1 0? : awk grep sed : awk '/ *\$0\.[0-9][0-9].*/' input_file 2) awk_pattern ( actions $1,$2)/regexp/ : : < > <= >= ==!= : value ~ /regexp/ value /regexp/ value!~ /regexp/ value /regexp/ : awk '$2 > 10 {print "ok"' input_file awk '$3 ~ /^d/ {print "ok"' input_file &&() () /regexp/!() /regexp/ : awk '($1 < 10 ) && ($2 > 10) {print "ok"' input_file awk '/^d/ /x$/ {print "ok"' input_file awk_script eg: awk '(tot+=$6); END{print "total points :" tot ' input_file // awk 'tot+=$6 {print $0 END{print "total points :" tot ' input_file //

19 awk ARGC ARGV FILENAME FNR FS RS NF NR OFS ORS 1awk '/101/' file file 101 awk '/101/,/105/' file awk '$1 == 5' file awk '$1 == "CT"' file awk '$1 * $2 >100 ' file awk '$2 >5 && $2<=15' file 2awk '{print NR,NF,$1,$NF,' file file awk '/101/ {print $1,$2 + 10' file file 10 awk '/101/ {print $1$2' file awk '/101/ {print $1 $2' file file 4 3df awk '$4> ' 4awk -F " " '{print $1' file awk 'BEGIN { FS="[: \t ]" {print $1,$2,$3' file FS="[: \t ]" Sep=" " Sep : awk -F $Sep '{print $1' file awk -F '[ :\t ]' '{print $1' file TAB awk -F '[][]' '{print $1' file [] 5awk -f awkfile file awkfile cat awkfile -- /101/{print "\047 Hello! \047" -- ' Hello! '.\047 {print $1,$2 6awk '$1 ~ /101/ {print $1' file 101 7awk 'BEGIN { OFS="%" {print $1,$2' file OFS="%"

20 8awk 'BEGIN { max=100 ;print "max=" max BEGIN {max=($1 >max?$1:max); print $1,"Now max is "max' file 1? 2: ( 3 if 1) 2 else 3 awk '{print ($1>4? "high "$1: "low "$1)' file 9awk '$1 * $2 >100 {print $1' file awk '{$1 == 'Chi' {$3 = 'China'; 7 print' 3 file 7 awk '{$7 %= 3; print $7' file 11awk '/tom/ {wage=$2+$3; printf wage' file wage 12awk '/tom/ {count++; END {print "tom was found "count" times"' file END 13awk 'gsub(/\$/,"");gsub(/,/,""); cost+=$4; END {print "The total is $" cost>"filename"' file filename gsub $, $1, $2, $4, awk '{gsub(/\$/,"");gsub(/,/,""); if ($4>1000&&$4<2000) c1+=$4; else if ($4>2000&&$4<3000) c2+=$4; else if ($4>3000&&$4<4000) c3+=$4; else c4+=$4; END {printf "c1=[%d];c2=[%d];c3=[%d];c4=[%d]\n",c1,c2,c3,c4"' file if else if awk '{gsub(/\$/,"");gsub(/,/,""); if ($4>3000&&$4<4000) exit; else c4+=$4; END {printf "c1=[%d];c2=[%d];c3=[%d];c4=[%d]\n",c1,c2,c3,c4"' file exit END awk '{gsub(/\$/,"");gsub(/,/,""); if ($4>3000) next; else c4+=$4;

21 END {printf "c4=[%d]\n",c4"' file next 14awk '{ print FILENAME,$0 ' file1 file2 file3>fileall fileall file1file2file3 15awk ' $1!=previous 3 { close(previous); previous=$1 {print substr($0,index($0," ") +1)>$1' fileall 16awk 'BEGIN {"date" getline d; print d' getline d date 17awk 'BEGIN {system("echo "Input your name:\\c""); getline d;print "\nyour name is",d,"\b!\n"' getline name awk 'BEGIN {FS=":"; while(getline< "/etc/passwd" >0) { if($1~"050[0-9]_") print $1' /etc/passwd 050x_ 18awk '{ i=1;while(i<nf) {print NF,$i;i++' file while awk '{ for(i=1;i<nf;i++) {print NF,$i' file for type file awk -F "/" ' { for(i=1;i<nf;i++) { if(i==nf-1) { printf "%s",$i else { printf "%s/",$i ' for if awk 'BEGIN { for(j=1;j<=12;j++) { flag=0; printf "\n%d \n",j; for(i=1;i<=31;i++) { if (j==2&&i>28) flag=1; if ((j==4 j==6 j==9 j==11)&&i>30) flag=1; if (flag==0) {printf "%02d%02d ",j,i 19 ' awk Flag=abcd awk '{print '$Flag'' abcd awk '{print "$Flag"' $Flag

44 - Text formating with awk Syntax: awk -FFieldSeperator /SearchPatern/ {command} File z.b. awk '/ftp/ {print $0}' /etc/services

44 - Text formating with awk Syntax: awk -FFieldSeperator /SearchPatern/ {command} File z.b. awk '/ftp/ {print $0}' /etc/services Exercises: awk: less /etc/passwd awk -F: '{print $1}' /etc/passwd awk -F: