all tasks

Task/Substring/UNIX-Shell/substring-2.sh

@@ -0,0 +1,17 @@
+str="abc qrdef qrghi"
+n=6
+m=3
+
+expr "x$str" : "x.\{$n\}\(.\{1,$m\}\)"
+expr "x$str" : "x.\{$n\}\(.*\)"
+expr "x$str" : "x\(.*\)."
+
+index() {
+	i=0 s=$1
+	until test "x$s" = x || expr "x$s" : "x$2" >/dev/null; do
+		i=`expr $i + 1` s=`expr "x$s" : "x.\(.*\)"`
+	done
+	echo $i
+}
+expr "x$str" : "x.\{`index "$str" r`\}\(.\{1,$m\}\)"
+expr "x$str" : "x.\{`index "$str" qr`\}\(.\{1,$m\}\)"