The solution of permission denied

When debugging the startup file , The following error occurred ：

Permission denied

The reason is that the permission of the file is not enough , The measured solutions are as follows ：

//  Be careful ：777 Use permissions with caution   For high permissions 
$ sudo chmod -R  xxx  A directory 
 
//  Define your own xxx, Here's a description 

among
-R Refers to cascading all subdirectories and files applied to the directory
750 Indicates that the file owner has read 、 Write 、 Executive authority , File group has read 、 Executive authority , Other users don't have permission

Belong to ：rwx=4+2+1=7.
Generic group ：r-x=4+0+1=5.
other ：---=0+0+0=0
write in 、 Read and execute permissions have the following numerical values ：

r ( read ) = 4
w ( Write ) = 2
x ( Executable ) = 1
No authority = 0
The permission number of a specific user class is the sum of the permission values of that class .

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Solve the problem after operation ,OK！