hi all
what is the meaning of this.
2> /dev/null
can u please explain.

thank you in advance

If I'm not completely mistaken it means that any error messages produced should be forwarded to /dev/null (instead of printing them to screen), effectively causing error messages not to be shown.

yeah! its ok.
but what is "2>". why we use this.

thank you in advance

">" (or "<") is the redirection operator. If it is not preceded by a number (the file designator) then it defaults to standard output (>) or standard input (<)

example:
cat filename|[some command] >newfilename
This takes data from filename and runs it thru [some command] and then send the output to newfilename.

using input redirection, it looks like this:
[some command] <filename >newfilename

(Note that it is more common to enclose metadata in <>, but that would really be confusing when describing the < and > operators)

To run a command and direct the output to a file and trash the errors:

[some command] 1>filename 2>/dev/null