#!/bin/bash

a=1
b=2
c=3

# if ($a < $b or $c < $b) then ...
if [ $a -lt $b ]; then
  echo "$a < $b"
fi

if [ $c -lt $b ]; then
  echo "$c < $b"
fi

if [ $a -lt $b -o $c -lt $b ]; then
  echo "$a < $b or $c < $b"
fi
