Changing the permissions can be done with names and numbers, I like the numbers
chmod 754 test.txt
Here is why:
4=read 2=write 1=execute.
The three numbers in the chmod above are for the
"user" ( the first number ),
"group" ( the second number ) and
"others" ( the third number )
So if I want to give the user all permissions: 4+2+1=7
and i give the group read an execute permissions: 4+1=5
and all others only read permission 4=4
chmod takes either the decimal representation of the permissions or a symbolic representation.
The symbolic representation is [ugoa][+-][rwx]. This is one of the letters
u (user=file owner),
g (group), o(others),
a (all=u and g and o) followed by + or - to add or remove permissions and then the symbolic representation of the permissions in the form of
To make the file "file.txt" writable for all you type: "chmod a+w file.txt"