用shell脚本实现每隔30s检查httpd进程存在与否，httpd存在时输出0，不存在输出1.方法一：单条命令实现catapache.sh#!/bin/bashwhiletruedops-ef|grephttp|grep-vgrep>/dev/null&&echo0||echo1sleep30donewhiletrue为真，一直执行do循环。#ps-ef|grephttp，过滤出http进程输出结果：root72861015:14?00:00:00/usr/sbin/httpdnagios72887286015:14?00:00:00/usr/sbin/httpdnagios72897286015:14?00:00:00/usr/sbin/httpdnagios72907286015:14?00:00:00/usr/sbin/httpdnagios72917286015:14?00:00:00/usr/sbin/httpdnagios72927286015:14?00:00:00/usr/sbin/httpdnagios72937286015:14?00:00:00/usr/sbin/httpdnagios72947286015:14?00:00:00/usr/sbin/httpdnagios72957286015:14?00:00:00/usr/sbin/httpdroot74404708015:17pts/000:00:00grephttp#ps-ef|grephttp|grep-vgrep,过滤ps-ef|grephttp本身。输出结果：root72861015:14?00:00:00/usr/sbin/httpdnagios72887286015:14?00:00:00/usr/sbin/httpdnagios72897286015:14?00:00:00/usr/sbin/httpdnagios72907286015:14?00:00:00/usr/sbin/httpdnagios72917286015:14?00:00:00/usr/sbin/httpdnagios72927286015:14?00:00:00/usr/sbin/httpdnagios72937286015:14?00:00:00/usr/sbin/httpdnagios72947286015:14?00:00:00/usr/sbin/httpdnagios72957286015:14?00:00:00/usr/sbin/httpd#ps-ef|grephttp|grep-vgrep>/dev/null，输出到空设备文件。#ps-ef|grephttp|grep-vgrep>/dev/null&&echo0||echo1逻辑与：&&，逻辑或：||。"ps-ef|grephttp|grep-vgrep>/dev/null"为真时执行echo0，否则执行echo1.方法二：catapache.shwhiletruehttpnum=`ps-ef|grephttp|grep-vgrep|wc-l`doif[$httpnum-gt0]thenecho0elseecho1fisleep30done方案二摘自老男孩博客http://oldboy.blog.51cto.com/2561410/577227，里面有详细介绍。