1、chmod
Reproduced below to https://blog.csdn.net/summer_sy/article/details/70142475
chmod u + x file.sh it means increased executable permissions for owner file.sh files in the current directory.
u represents the user
x stands for execute permission
g behalf of the user group.
o behalf of the other.
a representative of all.
+ To add permissions
This means that chmod u + x somefile granted permission only belongs to those who carried out this file
and chmod + x somefile and chmod a + x somefile is the same
Just doing + x will apply it to all flags: [u] ser, [g ] roup, [o] thers.