Permissions are represented by nine-character strings such as rwxr-xr-x and numeric values such as 755. The 9 character string consists of r(readable), w(writable), x(executable), and hyphen(-), which have the meanings.
The commonly used permission patterns are as follows.
644
normal HTML file etc. can read and write, but group members and others can only read.
666
files to be written by CGI script, etc. Both myself and group members and others can read and write.
755
Regular directories, commands, CGI script, etc. Everyone can read and execute, but write only oneself.
777
Directory for CGI scripts to create files. Anyone can do anything. Slightly dangerous on security.
