Whenever we execute ls command in UNIX you might have observed that it list file name with lot of details e.g.
stock_options:~/test ls -lrt
total 8.0K
-rw-r--r-- 1 stock_options Domain Users 1.1K Jul 15 11:05 sample
If you focus on first column you will see the file permissions as "-rw-r--r--" this is made of three parts user, group and others. User part is permission relate to user logged in, group is for all the members of group and others is for all others. also each part is made of three permissions read, write and execute so "rw-" means only "read and write" permission and "r--" means read only permission. So if you look permission of example file it has read and writes access for user, read only access for groups and others. Now by using chmod command in UNIX we can change the permissions or any file or directory in UNIX or Linux. Another important point to remember is that we need execute permission in a directory to go inside a directory; you can not go into directory which has just read and write permission.
