Bash flush standard input before a read

Question

Is there an easy way in bash to flush out the standard input?

I have a script that is commonly run, and at one point in the script read is used to get input from the user. The problem is that most users run this script by copying and pasting the command line from web-based documentation. They frequently include some trailing whitespace, or worse, some of the text following the sample command. I want to adjust the script to simply get rid of the extra junk before displaying the prompt.

Solution

This thread on nonblocking I/O in bash might help.

It suggests using stty and dd.

Or you could use the bash read builtin with the -t 0 option.

# do your stuff

# discard rest of input before exiting
while read -t 0 notused; do
   read input
   echo "ignoring $input"
done

If you only want to do it if the user is at a terminal, try this:

# if we are at a terminal, discard rest of input before exiting
if test -t 0; then
    while read -t 0 notused; do
       read input
       echo "ignoring $input"
    done
fi

Comments

[dribler]

I ended up going with a command like this. while read -e -t 1; do : ; done. This seemed to be adequate for what I needed.