`chmod` - change file mode bits

chmod [-R] MODE file...

Options you will use

-R, --recursive: Change files and directories recursively.
MODE (octal): 4=read 2=write 1=execute, per owner/group/other. 750 = rwxr-x---
MODE (symbolic): [ugoa][+-=][rwxXst], e.g. u+x, go-w, a=r, g+s

$ chmod 750 deploy.sh

owner full, group read+execute, others nothing

$ chmod +x script.sh

the missing bit behind half of the 203/EXEC failures

$ chmod 2775 /srv/shared

setgid: new files inherit the directory group

$ chmod 1777 /tmp

sticky: only the owner can delete their own files

On a DIRECTORY: r = list the names, x = traverse into it and stat files by name. x without r means you can read a file whose name you already know but cannot ls.

Try chmod in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.