Set File Permissions
Also, take a look at the chmod reference.
$ ls -lst apple.txt 1 -rw-r--r-- 1 december december 21 Dec 19 21:19 apple.txt $ chmod 755 apple.txt $ ls -lst apple.txt 1 -rwxr-xr-x 1 december december 21 Dec 19 21:19 apple.txt* $ chmod 700 apple.txt $ ls -lst 1 -rwx------ 1 december december 21 Dec 19 21:19 apple.txt* $ chmod 444 apple.txt $ ls -lst apple.txt 1 -r--r--r-- 1 december december 21 Dec 19 21:19 apple.tx $