UNIX for Dummies Questions & Answers

Nice!

RudiC's solution for Unix sed (that wants multi-line and a space after the w command and a ; before a })

Code:

sort file | sed -n '
/X/,${p;d;}
w TMP' | cat - TMP && rm TMP

With shell code

Code:

sort file | while read line
do
  case $line in *X*) x=1;; esac
  if [ "$x" ]; then echo "$line"; else echo "$line" >&3; fi
done 3>TMP | cat - TMP && rm TMP

Now the experts question.
I am wondering if there could be a race condition - TMP is not yet flushed when cat opens it.
I think the order of the cat arguments makes it, first - then TMP.
But what happens if the stdout is closed before the TMP? And in the microsecond between the cat starts reading from TMP? Is this possible?