sed command problem

I am cating a file with passwords into another file. I want to replace the the password with **** and it is not working. Here is my command

cat testing | sed 's/`echo ${pass}`/*****/'>>out1

${pass} is the password that I want to replace before it goes into out1

Anyone know what I am doing wrong?

Your sed command is between apostrophes (single quotes) rather than quotes (double quotes). This prevents the expansion of ${pass}. You don't need to worry about filename globbing if you switch to quotes, since quoted asterisks are not expanded by the shell.