How to check whether a file have immutable flag/attribute or not without using lsattr command?
 

We can use lsattr command to check the immutable flag of a file, But I want to know that is there any other way or command to check such flag or attributes?

Not that I know of.

Typically commands which have alternatives contain those suggestions in the SEE ALSO part of the man page. Check that out.

you can use an EXT2 or EXT3 filesystem without support for attr, and insure you have it disabled in Kernel

in that case you don't need to check attr because they aren't there

(your linux distro may demand access and use of such attr, though)

other than that, attr are complicated enough if you need to check them (hopeing to check security) you may not gain much: the situation is too comlex when P.A.M. and "linux libs setting attr" get in the picture: you may not know enough to set the right attr right? you have to assume they are pretty good or you got allot of work to do.