chmod 660 (rw-rw----)

chmod 660 (rw-rw----) gives the owner read and write, the group read and write, and everyone else no permissions.

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Symbolic rwxr-xr-x
Read (4)Write (2)Execute (1)
Owner
Group
Others
Special
chmod 755 file

What chmod 660 means

ClassDigitPermissions
Owner6read and write
Group6read and write
Others0no permissions

Group-writable: fine for shared deploy directories, but make sure the group only contains trusted users.

chmod 660 file.txt          # one file
find /var/www -type f -exec chmod 660 {} +   # all files in a tree

How octal permissions work

Each digit is the sum of read (4), write (2) and execute (1) for owner, group and others. So 7 = 4+2+1 = rwx, 5 = 4+1 = r-x, 4 = r--. An optional leading digit sets special bits: setuid (4), setgid (2) and sticky (1) โ€” e.g. 1777 is /tmp.

Safe defaults for web servers

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