Transcript awk 入門
AWK 入門
Advisor: Quincy Wu Speaker: Kuan-Ta Lu Date: July 8, 2010
What Is AWK?
是一種可以處理資料、產生格式化報表的語言， 功能相當強大。 awk的工作方式是讀取資料檔，將每一列資料視 為一筆記錄（record），每筆記錄以欄位分隔符 號分成若干欄位，然後，輸出各個欄位的值。 需要具備正規表示式的基本知識。 2
awk 的用法 (1)
awk '條件類型1{動作1} 條件類型2{動作2} ...' filename $ awk '{ print }' /etc/passwd $ awk -F":" '{ print $1 }' /etc/passwd $ ls -l /etc | awk '{print $1 "\t" $9}' 3
awk 的用法 (2)
$ awk '{print $2,$3}' emp_names $ awk '/AL/ {print $3,$2}' emp_names $ awk '/AL/ {print $3,$2 ; print $4,$5}' emp_names $ awk '/AL/ {print $3,$2} {print $4,$5}' emp_names $ awk '/AL/ {print $3,$2 ; print $4", "$5"\n"}' emp_names 4
awk 的用法 (3)
$ awk '/AL|IN/' emp_names $ awk '$5 ˜ /AR/' emp_names $ awk '$5 !˜ /AR/' emp_names 5
awk 的變數 (1)
變數 NF 每一行 ($0) 擁有的欄位總數 NR 目前 awk 所處理的是『第幾行』資料 FS 目前的分隔字元，預設是空白鍵 RS 記錄的分隔字元，預設是行 OFS 輸出分隔字元 ORS 輸出記錄分隔字元，預設是行 $ last | awk '{print $1 "\t lines: " NR "\t columes: " NF}' 6
awk 的變數 (2)
$ awk '{FS=":"}{print $2}' mou_names $ awk -F":" '{OFS="-"}{print $1,$2,$3,$4,$5}' mou_names $ awk -F":" '{print NR,$1,$2,$3}' mou_names $ awk -F":" '/4601[2-5]/' mou_names 7
awk 的運算 (1)
邏輯運算 > 大於 < 小於 >= 大於或等於 <= 小於或等於 == 等於 != 不等於 數學運算 + adds numbers together - subtracts * multiplies / divides 8
awk 的運算 (2)
^ performs exponential mathematics % gives the modulo ++ adds one to the value of a variable += assigns the result of an addition operation to a variable -- subtracts one from a variable -= assigns the result of a subtraction operation to a variable *= assigns the result of multiplication /= assigns the result of division %= assigns the result of a modulo operation cat /etc/passwd | awk '{FS=":"} $3 < 10 {print $1 "\t " $3}' 9
awk 的運算 (3)
$ cat pay | awk 'NR==1{printf "%10s %10s %10s %10s %10s\n",$1,$2,$3,$4,"Total"} NR>=2{total=$2+$3+$4 printf "%10s %10d %10d %10d %10.2f\n",$1,$2,$3,$4,total}‘ $ awk '{print $1,"QTY: "$2,"PRICE: "$3,"TOTAL: "$2*$3}' inventory 10
awk 的運算 (4)
$ awk '{x=x+$2} {print x}' inventory $ awk '{x=x+($2*$3)}{print $1,"QTY: "$2,"PRICE: "$3,"TOTAL: "$2*$3,"BAL: "x}' inventory $ awk '{x=x+($2*$3)} {print $1,"QTY: "$2,"PRICE: "$3,"TOTAL: "$2*$3} END {print "Total Value of Inventory: " x}' inventory 11
awk 的運算 (5)
$ sort emp_names | awk '{print $3,$2}' $ awk '{print NR, $1 > "/tmp/filez" }' emp_names $ awk '{ print $2 | "sort" }' emp_names 12
$ cat g-than #!/bin/awk -f BEGIN{ lowerbound = 55 } /^#/ { print $0 } ! /^#/ { for(i=1; i<=NF; i++) if( $i > lowerbound ) print $i }
Example (1)
$ cat N # just a test 33 22 999 223 44 55 99 $ ./g-than N # just a test 999 223 99 13
$ cat sum-fields #!/bin/awk -f /^#/ { print $0 } ! /^#/ { name = "" sum = 0 for(i=1; i<=NF; i++) if( $i ~ /[0-9][-9]*/ ) sum = sum + $i else name = name $i print name "=" sum }
Example (2)
$ cat > IN 233 112 33 # oh!, just a test # again 333 hi kk 22 $ ./sum-fields IN =378 # oh!, just a test # again hikk=355 14
$ cat > sum-vars #!/bin/awk -f /^#/ { print $0 } ! /^#/ { name = $1 sum = 0 for(i=2; i<=NF; i++) sum += $i var[ name ] += sum }
Example (3)
} END{ for (v in var) printf "%s = %d\n", v, var[v] $ cat > IN-num klim 233 112 33 # oh!, just a test # again milk 333 22 klim 999 22 oak 222 redcow 1023 oak 11 milk 333 22 $ ./sum-vars IN-num # oh!, just a test # again redcow = 1023 klim = 1399 oak = 233 milk = 710 15
Exercises
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/etc/passwd 以冒號 “:“ 作為欄位的分隔，如 何查閱第三欄小於等於 50 以下的數據，並且僅 列出帳號與第三欄以tab隔開？ 利用awk計算出檔案 sshreport.pl
有幾行空白行？ 寫一個awk script, 功能如下: $ cat ex-input # klim 23 33 22 11 8888 42 # oak 1000 200 2200 -22 -3000 -20 -3 # redcow 20000 20000 # ryan 73 94 -94 $ ./ex.awk ex-input oak 355 klim 9019 ryan 73 redcow 40000 16
Reference
http://www.oracle.com/technology/pub/articles/dula ney_awk.html
http://www.cyut.edu.tw/~dywang/linuxProgram/nod e20.html
http://www.vectorsite.net/tsawk_2.html
http://www.study area.org/cyril/scripts/scripts/node61.html
http://www.grymoire.com/Unix/Awk.html
http://nixchun.pixnet.net/blog/post/21760238 http://erdos.csie.ncnu.edu.tw/~klim/ 17