linux shell---if condition

Syntax:

if conditionthencommand1 if condition is true or if exit statusof condition is 0 (zero)......       fi                                                                                     

if given condition is true then command1 is executed

For compression you can use test or [ expr ] statements or even exist status can be also used.

eg.

#!/bin/bash
#
#Script to print file
#
if cat $1
then
echo -e "\n\nFile $1, found and successfully echoed"
fi

$0执行shell的时候表示的是shell name，$1表示执行shell时候传递的第一个参数，依次类推。$#表示执行shell的时候传递的参数的个数。