echo to stderr and tee to log file?

Question

In bash script,

echo \"error\" 1>&2 | tee -a log

will print stderr in screen but no log to file, how to do these at same tim

Answer 1

echo "error" 1>&2 | tee -a log

With the first part 1>&2, what you are saying is: "Redirect stdout to stderr". So the echoed output "error" goes to stderr.

Pipe (|) only reads from stdout, not stderr. So tee doesn't get any stdin at all from the pipe. Hence, it appends nothing to the log file.