October 22, 2009
bash’s built-in read may behave unexpectedly. I’m not sure exactly why, but it looks like it has to do with it expecting to be invoked in a loop. Here’s what I expected to work:
$ echo "thisisfirst thisissecond" | read first second
$ echo $first
$ echo $second
Wait, what? But I use read all the time for while loops like this:
cat file | while read col1 col2 col3; do
printf "col1: %sncol2: %sncol3: %snn" $col1 $col2 $col3
done
and that has never let me down. So why can’t I do it this way? I don’t really know, do you? Here’s a work around:
echo "thisisfirst thisissecond" | while read first second; do
#do junk here
done