Shell programming core technology "four"

The content shared today is similar to Shell Programming core technology 《 3、 ... and 》 It's linked , It needs to be read together .

function

Next , We package it into a tester_level function , After having functions, they can be called at any time during the execution process to realize function encapsulation and logic reuse .

You can see from the picture above , call test_001.sh Script and pass in a parameter ：java, It didn't output what we expected java auto tester, The reason is that only defining functions will not be implemented , For example, no relevant information is output at this time auto tester result .

And we run tester_level Function and will 2 Pass parameters to it , here 2 Is the second parameter of the script , But it is tester_level First argument to function .

Execute the script , Pass in a parameter java, No display , One more python Still no response , Until incoming python java After two parameters , Just output java auto tester, because tester_level The second parameter of the whole script is received .

Permission bit execution Shell Script

Through the demonstration of the previous case, we have mastered the use sh Execute the script , But if we Do not want to use sh Execute the script , If you want the system to parse automatically , It can be realized by weighted limit .

First of all to see test_001.sh What is the current permission bit of , You can use commands ：ls -l /tmp/test_001.sh, As shown in the figure above , It can be found that there is no x, That is, there is no executable permission .

When we directly enter the command ：/tmp/test_001.sh, namely test_001.sh When the full path of the file is , Wrong presentation ：Permission denied No execution permission .

As shown in the figure above , Use command ：chmod +x /tmp/test_001.sh Add executable permissions to files .

As shown in the figure above , When no document is given test_001.sh When adding executable permissions to a file , Direct use command ：/tmp/test_001.sh It's a newspaper permission denied Wrong , But when you add executable permissions to the file , Use the command again ：/tmp/test_001.sh When executing a script , It can be executed successfully , No report error .

add to PATH Variable fast execution Shell Script

If test_001.sh The full path of the file is very long , Such as /user/candy/python/shell/project_person_tmp/test_001.sh, We want to execute test_001.sh file , Follow the method described above , Need to enter test_001.sh The full path of the file can be executed , This is too complicated , Remember clearly every time you execute test_001.sh The full path of the file and enter , Is there a simpler way , If you only enter the file name ：test_001.sh You can run the script directly ？ The answer is yes .

The solution is ： take /tmp This path adds to PATH variable , Enter test_001.sh If the command is executed directly, there will be no more errors .

Shell Debug during script execution

When our Shell The script is wrong , How to debug during execution ？

As shown in the figure above , have access to sh -x command , It can print every command line of the current script when the script is running , When the script goes wrong, you can know which line went wrong , It passes by + The output at the beginning shows which line is currently being executed Shell Code , With it, debugging becomes very convenient .

Friendship tips ：“ The way of immeasurable testing ” Original works , Welcome to exchange , It is forbidden for a third party to reprint the article without displaying its source .