How to pass the value of a variable to the stdin of a command?

Question

I\'m writing a shell script that should be somewhat secure i.e. does not pass secure data through parameters of commands and preferably does not use temporary files. How can

Answer 1

As per Martin's answer, there is a bash feature called Here Strings (which itself is a variant of the more widely supported Here Documents feature).

http://www.gnu.org/software/bash/manual/bashref.html#Here-Strings

3.6.7 Here Strings

A variant of here documents, the format is:

<<< word

The word is expanded and supplied to the command on its standard input.

Note that Here Strings would appear to be bash-only, so, for improved portability, you'd probably be better off with the original Here Documents feature, as per PoltoS's answer:

( cat <

Or, a simpler variant of the above:

(cmd <

You can omit ( and ), unless you want to have this redirected further into other commands.