Difference between cp and cp -p -i

Question

I am using cp command in my program to make a copy of a text file. But when I use -p -i with cp I don't understand the difference between the both.

What's the difference between using simple cp and using options -p -i with it? Here is my line code:

execl("/bin/cp","cp","-p","-i",argv[1],argv[2],NULL);

...though since `-i` is a POSIX-standardized option, you could also read http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cp.html — Charles Duffy, Mar 10 '15 at 15:58
@CharlesDuffy: i did bro but that's not enough plus i am new to linux — Syed Dawood, Mar 10 '15 at 15:58
Then show your work! If you explain what you got from the man page and why you don't understand it, that would go a long way to have people not blowing you off for failing to do your homework. — Charles Duffy, Mar 10 '15 at 15:59
@CharlesDuffy: i did code successfully and its working all i wanted was to make myself clear,well thanks for your help :) — Syed Dawood, Mar 10 '15 at 16:03

score 0 · Accepted Answer · answered Mar 10 '15 at 16:32

The -i stands for interactive mode, this will require input from the stdin before it will overwrite a file. The -p (no capital p) will preserve mode ownership and timestamp. The latter one seems the more interesting one, this will actually cause a difference in your mss. When you're copying a file there is an owner of the file and there are different file permissions and a timestamp attached to it, if you want to keep these then use the -p parameter.

Difference between cp and cp -p -i

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