piping the output to another command

The diff command works only if it has been provided with 2 files. Is it possible to replace one file with the output of another comma开发者_Python百科nd? The second command mentioned below does not work.

$ mysqldump -ushantanu -pPassWord test tbl --skip-extended-insert > to_backup.sql

$ diff  `mysqldump -uroot -pPassWord test some_other_tbl --skip-extended-insert` to_backup.sql 
-bash: /usr/bin/diff: Argument list too long

In bash you can use process substitution.

diff <(mysqldump ...) to_backup.sql

You can pipe one file from stdin

 $ mysqldump -uroot -pPassWord test some_other_tbl --skip-extended-insert | diff  to_backup.sql - 

You can use - as a special file name to represent standard input:

$ echo foo > bar
$ echo foo > baz
$ cat bar | diff - baz

or

$ mysqldump -uroot -pPassWord test some_other_tbl --skip-extended-insert | diff - to_backup.sql