open system call in linux
 

in open system call : what does mode implies and what all values does it takes.

Mode is used to set the default permissions when creating a file. The following example will create a file with read and write permissions for user, group and other (UGO).

open(path, O_RDWR | O_CREAT, 0666);

Read the manual page of chmod to find out how all those numbers work.