chmod 755 — what rwxr-xr-x means
755
rwxr-xr-x
The owner can read, write, and execute; the group and everyone else can read and execute but not modify.
Permission breakdown
When to use 755
The standard for directories and for executable scripts or binaries that others need to run but not change. Web server document roots and CLI tools usually sit at 755.
Set it with chmod
Apply this permission to a file:
chmod 755 filename
Or apply it recursively to a directory and everything inside it:
chmod -R 755 directory/
Other common permissions
Or build any permission with the interactive chmod calculator.