sed 命令及shell的if语句的运用实例

if [ -f /etc/syslog.conf ];     #判断文件是否存在
then
systest=`sed -n  '/^auth.info/p' /etc/syslog.conf`;    #匹配/etc/syslog.conf文件中是否有auto.info字符串,并返回字符串,systest变量接收。
if [ -n "$systest" ];                                               #判断字符串是否存在
then
sed -e 's/^auth.info.*/auth.info        \/var\/adm\/authlog/g' /etc/syslog.conf > config.tmp && mv config.tmp /etc/syslog.conf;  #存在则替换
else
awk '{print $0} END{print "auth.info        /var/adm/authlog"}' /etc/syslog.conf > config.tmp && mv config.tmp /etc/syslog.conf; #不存在则在最后一行添加,solaris系统下不支持sed -i时使用。

sed -i '$a auth.infos    /var/adm/authlogs' /etc/syslog.conf;      #不存在则在最后一行添加。 redhat,suse
fi;                                                                              #第一个内层判断结束
syserr=`sed -n  '/^*.err;auth.info/p' /etc/syslog.conf`;
if [ -n "$syserr" ];
then
sed -e 's/^*.err;auth.info.*/*.err;auth.info        @${loghost}/g' /etc/syslog.conf > config.tmp && mv config.tmp /etc/syslog.conf;
else
awk '{print $0} END{print "*.err;auth.info        @${loghost}"}' /etc/syslog.conf > config.tmp && mv config.tmp /etc/syslog.conf;
fi;                                                                         #第二个内层判断结束
fi;                                                                      
if [ -f /var/adm/authlog ];
then
echo "/var/adm/authlog exist.";
else
touch /var/adm/authlog;                                #创建文件
chown root:system /var/adm/authlog;             #赋权
chmod 600 /var/adm/authlog;                         #赋权
echo "create file /var/adm/authlog.";
fi;";

原文地址:https://www.cnblogs.com/resie/p/4796967.html