调试 shell script 方法

wade@V1088:~$ cat b.sh
#!/bin/bash
dir=`pwd`
dir=$dir'/'
for f in `ls *.png`
do

  echo $dir$f
done

看每一行代码的执行：

wade@V1088:~$ bash -x b.sh
++ pwd
+ dir=/home/wade
+ dir=/home/wade/
++ ls chrome_1407299385726.png chrome_1427299385726.png
+ for f in '`ls *.png`'
+ echo /home/wade/chrome_1407299385726.png
/home/wade/chrome_1407299385726.png
+ for f in '`ls *.png`'
+ echo /home/wade/chrome_1427299385726.png

进一步，看具体执行的代码与行号对应：

wade@V1088:~$ export PS4='+${BASH_SOURCE}:${LINENO}:${FUNCNAME[0]}: '
wade@V1088:~$ bash -x b.sh
++b.sh:2:: pwd
+b.sh:2:: dir=/home/wade
+b.sh:3:: dir=/home/wade/
++b.sh:8:: ls chrome_1407299385726.png chrome_1427299385726.png
+b.sh:4:: for f in '`ls *.png`'
+b.sh:7:: echo /home/wade/chrome_1407299385726.png
/home/wade/chrome_1407299385726.png
+b.sh:4:: for f in '`ls *.png`'
+b.sh:7:: echo /home/wade/chrome_1427299385726.png

指定脚本的部分去跑详细的行号，其余的忽略：

wade@V1088:~$ cat b.sh 
#!/bin/bash
dir=`pwd`
dir=$dir'/'
#this line above won't log out 
set -x
for f in `ls *.png`
do

  echo $dir$f
done
set +x
#the follow line won't log out 
echo 'end'
abc='new var'

运行输出：

wade@V1088:~$ ./b.sh
++./b.sh:10:: ls chrome_1407299385726.png chrome_1427299385726.png
+./b.sh:6:: for f in '`ls *.png`'
+./b.sh:9:: echo /home/wade/chrome_1407299385726.png
/home/wade/chrome_1407299385726.png
+./b.sh:6:: for f in '`ls *.png`'
+./b.sh:9:: echo /home/wade/chrome_1427299385726.png
/home/wade/chrome_1427299385726.png
+./b.sh:11:: set +x
end