Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
The aim is to not even start $foo if there is no input.
This can be useful if foo=”diff – xyz”, and the input is missing or empty.
Otherwise, diff would output all of “xyz” as the difference.
The original problem is that “cat doesnotexist | diff – exists” outputs the content of “exists” (prefixed with “>”), while I want the entire pipe to fail.
My current solution is:
cat doesnotexist | (read first|| exit 1; (echo "$first"; cat) | diff - exists)
, but I would like a shorter one.
I removed the pipe, it has no added value in your example. Strictly, this doesn’t let the diff fail, it’s just not executed.