--- ./bookman.orig
+++ ./bookman
@@ -83,9 +83,9 @@
 shift $(($OPTIND - 1))
 date=${date:-$(date +'%d %B %Y')}
 
-[[ $1 ]] || set -- $(while read; do echo $REPLY; done)
+[ -n "$1" ] || set -- $(while read REPLY; do echo $REPLY; done)
 
-[[ $outfile ]] && post="$post >$outfile"
+[ -n "$outfile" ] && post="$post >$outfile"
 
 {
 	# Compute table of content from postscript output.