Shell调试技术小结

2012-10-08

Shell调试技术总结4 a65 b26 c307 while :8 do9 if (( $a 10 ))10 ? then break11 fi12 ? let a$a

Shell调试技术总结

4 a=6

5 b=2

6 c=30

7 while :

8 do

9 if (( $a >= 10 ))

10 ? then break

11 fi

12 ? let "a=$a+2"

13 ? let "b=$b*2"

14 ? ? let "c=$c-10"

15 done

[root@localhost shell]# sh trapdebug

before execute line: 4 a=,b=,c=

before execute line: 5 a=6,b=,c=

before execute line: 6 a=6,b=2,c=

before execute line: 7 a=6,b=2,c=30

before execute line: 9 a=6,b=2,c=30

before execute line: 12 a=6,b=2,c=30

before execute line: 13 a=8,b=2,c=30

before execute line: 14 a=8,b=4,c=30

before execute line: 7 a=8,b=4,c=20

before execute line: 9 a=8,b=4,c=20

before execute line: 12 a=8,b=4,c=20

before execute line: 13 a=10,b=4,c=20

before execute line: 14 a=10,b=8,c=20

before execute line: 7 a=10,b=8,c=10

before execute line: 9 a=10,b=8,c=10

before execute line: 10 a=10,b=8,c=10

before execute line: 16 a=10,b=8,c=10

2 then

3 echo "Debugging information: "

4 、、、、

5 fi

5 then

6 $@

7 fi

8 }

9 a=0

10 b=2

11 c=100

12 DEBUG echo "a=$a b=$b c =$c" #第1个调试钩子

13 while :

14 do

15 DEBUG echo "a=$a b=$b c =$c" #第个调试钩子

16 if (( $a >= 10 ))

17 then

18 break

19 fi

20 let "a=$a+2"

21 let "b=$b*2"

22 let "c=$c-10"

23 done

[root@localhost shell]# export DEBUG=true

[root@localhost shell]# sh debugblock

a=0 b=2 c =100

a=2 b=4 c =90

a=4 b=8 c =80

a=6 b=16 c =70

a=8 b=32 c =60

a=10 b=64 c =50

6 echo "ok ,continue";

7 elif [ "$yn" == "$N" ] || [ "$yn" == "$n"]; then

8 echo "oh ,interrupt!";

9 else echo "I don't know what is your choise"

10 fi

[root@localhost shell]# sh else

+ export PATH

+ read -p 'Please input (Y/N)'

Please input (Y/N)y

+ '[' '' == '' ']'

+ echo 'ok ,continue'

ok ,continue

5 then

6 return 1

7 else

8 return 0

9 fi

10 }

11 echroot()

12 {

13 isroot

14 if [ "$?" -ne 0 ]

15 then

16 echo "I'm not root"

17 else

18 echo "I'm root"

19 fi

20 }而且

21 #对PS4赋值，定制-x选项的提示符

22 export PS4='+{$LINENO: ${FUNCNAME[0]}:${FUNCNAME[1]}}'

23 echroot

[root@localhost shell]# sh -x nestfun

+ export 'PS4=+{$LINENO: ${FUNCNAME[0]}:${FUNCNAME[1]}}'

+ PS4='+{$LINENO: ${FUNCNAME[0]}:${FUNCNAME[1]}}'

+{23: :}echroot

+{13: echroot:main}isroot

+{4: isroot:echroot}'[' 0 -ne 0 ']'

+{8: isroot:echroot}return 0

+{14: echroot:main}'[' 0 -ne 0 ']'

+{18: echroot:main}echo 'I'\''m root'

I'm root

总结：针对Shell脚本中所遇到的错误进行了分析，对于逻辑错误进行的全面分析，trap能够代替echo方便的用于脚本输出信息，对撼树进行跟踪等。tee运用管道，便于清晰的看出管道间的数据流向，调试钩子借鉴于高级程序语言，是很好的编程风格，Shell选项不改变脚本内容，-n和-x选项是常见的脚本调试手段，-n主要用于脚本语法错误的调试，-x主要用于脚本的逻辑错误的调试。

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