1. AWK 入門 Advisor: Quincy Wu Speaker: Kuan-Ta Lu Date: July 8, 2010

2. 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

3. 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

4. awk 的用法 (2)  $ awk '{print $2,$3}' emp_namesemp_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

5. awk 的用法 (3)  $ awk '/AL|IN/' emp_names  $ awk '$5 ˜ /AR/' emp_names  $ awk '$5 !˜ /AR/' emp_names 5

6. 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

7. awk 的變數 (2)  $ awk '{FS=":"}{print $2}' mou_namesmou_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

8. 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

9. 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

10. awk 的運算 (3)  $ cat pay | awk 'NR==1{printf "%10s %10s %10s %10s %10s\n",$1,$2,$3,$4,"Total"}pay 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}' inventoryinventory 10

11. 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

12. 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

13. Example (1) $ cat g-than #!/bin/awk -f BEGIN{ lowerbound = 55 } /^#/ { print $0 } ! /^#/ { for(i=1; i<=NF; i++) if( $i > lowerbound ) print $i } 13 $ cat N # just a test 33 22 999 223 44 55 99 $./g-than N # just a test 999 223 99

14. Example (2) $ 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 } 14 $ 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

15. Example (3) $ cat > sum-vars #!/bin/awk -f /^#/ { print $0 } ! /^#/ { name = $1 sum = 0 for(i=2; i<=NF; i++) sum += $i var[ name ] += sum } END{ for (v in var) printf "%s = %d\n", v, var[v] } 15 $ 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

16. Exercises 1./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？ 2. 利用 awk 計算出檔案 sshreport.pl 有幾行空白行？ sshreport.pl 3. 寫一個 awk script, 功能如下 : 16 $ cat ex-input # klim 23 33 22 11 8888 42 # oak 1000 200 2200 -22 -3000 -20 -3 # redcow 20000 # ryan 73 94 -94 $./ex.awk ex-input oak 355 klim 9019 ryan 73 redcow 40000

17. Reference  http://www.oracle.com/technology/pub/articles/dulaney_a wk.html http://www.oracle.com/technology/pub/articles/dulaney_a wk.html  http://www.cyut.edu.tw/~dywang/linuxProgram/node20.ht ml http://www.cyut.edu.tw/~dywang/linuxProgram/node20.ht ml  http://www.vectorsite.net/tsawk_2.html http://www.vectorsite.net/tsawk_2.html  http://www.study- area.org/cyril/scripts/scripts/node61.html http://www.study- area.org/cyril/scripts/scripts/node61.html  http://www.grymoire.com/Unix/Awk.html http://www.grymoire.com/Unix/Awk.html  http://nixchun.pixnet.net/blog/post/21760238 http://nixchun.pixnet.net/blog/post/21760238  http://erdos.csie.ncnu.edu.tw/~klim/ http://erdos.csie.ncnu.edu.tw/~klim/ 17