linux sh 读取文件内容，if判读语句，变量var打印

#!/bin/bash
#1 读取文件 并显示
cat state.txt | while read line
do
echo $line
done#2 读取文件 并显示
cat state.txt | while read line; do echo $line; done#3 读取一个文件内容到一个变量中
var=$(cat state.txt)
echo $var
#4 根据变量进行判读
if [ $var==0 ]; then
echo "no run"
elif [ $var==1 ]; then
echo "run"
else
echo "error"
fi

import os def writePid():
pid = str(os.getpid())
f = open('athena.pid', 'w')
f.write(pid)
f.close()