Use the difference between "Chmod a + X" and "Chmod 755" [closed] - difference between using "Chmod a + X" and "Chmod 755" [closed]

problem ：

This may sound silly, but I have a file/ script that need to run and in order to do it I must change it to become executable. This may sound stupid , But I have a file to run / Script , To do this , I have to change it to an executable .I would want to use either chmod a+x or chmod 755 . I want to make ​​ use chmod a+x or chmod 755 .But is there a difference between using chmod a+x and chmod 755 ? But use chmod a+x and chmod 755 Is there a difference between ？

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Solution ：

Reference resources ： https://stackoom.com/en/question/1G1s2