chmod : change file mode bits
[SYNOPSIS] chmod OPTION MODE FILE/DIRECTORY
OPTION
# chmod 644 /home/test.txt
Change permissions of [/home/test.txt] to [644]
# chmod a+rx /home/test.sh
Add rx (read,execute) access to a (=ugo : user,group,other) in [/home/test.sh]
-R
change files and directories recursively
-v
output a diagnostic for every file processed