Thanks for shared article with us.. It is really good, I cleared my confussion when I was read your document.

small “s” – symbolically says the file has no execute persmission
capital “S’ – has sticky bit , suid or sgid enables with execute permission

for example:
rwSrwxrwx — has no execute permission for the owner/normal user who runs a script if applicable

where as

rwsrwxrwx — is sound meaningful.

[root@linux ~]# ls -l /usr/bin/mytest
-rwsr-xr-x 1 root root 52 Sep 9 08:41 /usr/bin/mytest
[root@linux ~]# ls -l /etc/myfile
-rw-r–r– 1 root root 24 Sep 9 08:41 /etc/myfile

First thing you need to SUID to your script created under /usr/bin/. Can you send me the result of ls -l of both files ?

Thank you for nice post,
But I have question, I try to create a script under /usr/bin/ directory after that i created a file uder /etc dir and give the . And give the permision chmod u+s /etc/filename, now i try to run as a normal user , it is running but not able to edit this file /etc/filename ???
where as you said after passwd command , there will some changes in /etc/shaddow and /etc/passwd file ..

Please help me

Thank you very much.
David