扫盲

pgrep tail | xargs kill -9 #xargs：通过缓冲方式并以前面命令行的输出作为参数

kill -9 `pgrep tail`

find /root -name 11.sh -exec rm {} \;

cat 22.sh 1>/dev/null 标准输出：只输出错误信息。

cat 22.sh 2>/dev/null #标准错误输出：只输出正确结果。

log=/tmp/`date "+%Y-%m-%d_%H_%M"`.top

echo "11" >> $log　　　　#生成日志

top -p 1 -b -d 1 -n 1|awk 'BEGIN{print strftime("%Y-%m-%d %H:%M:%S");}'

awk 'BEGIN{print strftime("%Y %m %d %H:%M:%S", 1324)}'

awk 'BEGIN{print strftime("%Y-%m-%d %H:%M:%S");}' >> asas.log
top -p 1 -b -d 1 -n 1 >> asas.log

ctrl + z 后台运行

jobs 查看后台运行的进程

fg 将后台运行的进程调到前台。

返回值为字符,会报错：

return "my name is bixiaopeng"

Shell自定义函数总结.sh: line 6: return: my: numeric argument required

1.变量通过" "引号引起来

#!/bin/sh
para1=
if [ ! -n "$para1" ]; then
  echo "IS NULL"
else
  echo "NOT NULL"
fi

4.使用""判断

?
#!/bin/sh 
dmin=
if [ "$dmin" = "" ]
then
  echo "dmin is not set!"
else 
  echo "dmin is set !"
fi
　　
?
#自动挂载Swap
autoSwap()
{
    swap=`free |grep Swap|awk '{print $2}'`
    if [ $swap -gt 1 ];then
        echo "Swap total sizse: $swap";
        return;
    fi
    if [ ! -d /www ];then
        mkdir /www
    fi
    swapFile='/www/swap'
    dd if=/dev/zero of=$swapFile bs=1M count=1025
    mkswap -f $swapFile
    swapon $swapFile
    echo "$swapFile    swap    swap    defaults    0 0" >> /etc/fstab
    swap=`free |grep Swap|awk '{print $2}'`
    if [ $swap -gt 1 ];then
        echo "Swap total sizse: $swap";
        return;
    fi
     
    sed -i "/\/www\/swap/d" /etc/fstab
    rm -f $swapFile
}
autoSwap
 
#判断kernel-headers组件是否安装
rpm -qa | grep kernel-headers > kernel-headers.pl
kernelStatus=`cat kernel-headers.pl`
#判断华为云
huaweiLogin=`cat /etc/motd |grep 4000-955-988`
huaweiSys=`cat /etc/redhat-release | grep ' 7.'`
if [ "$kernelStatus" = "" ]; then
    if [ "$huaweiLogin" != "" ] && [ "$huaweiSys" != "" ]; then
        wget $download_Url/src/kernel-headers-3.10.0-514.el7.x86_64.rpm
        rpm -ivh kernel-headers-3.10.0-514.el7.x86_64.rpm
        rm -f kernel-headers-3.10.0-514.el7.x86_64.rpm
    else
        yum install kernel-headers -y
    fi
fi
rm -f kernel-headers.pl
　　
安装ntp，并同步时间
?
yum install ntp -y
rm -rf /etc/localtime
ln -s /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
 
#尝试同步时间(从bt.cn)
echo 'Synchronizing system time...'
v1=$(curl http://www.bt.cn/api/index/get_time)
date -s "$(date -d @$v1 +"%Y-%m-%d %H:%M:%S")"
 
#尝试同步国际时间(从ntp服务器)
ntpdate 0.asia.pool.ntp.org
　　
 
?
startTime=`date +%s`
setenforce 0
sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
for pace in python-devel python-imaging zip unzip openssl openssl-devel gcc libxml2 libxml2-devel libxslt* zlib zlib-devel libjpeg-devel libpng-devel libwebp libwebp-devel freetype freetype-devel lsof pcre pcre-devel vixie-cron crontabs icu libicu-devel c-ares;
do
    yum -y install ${pace}; 
done
 
if [ -f "/usr/bin/dnf" ]; then
    dnf install -y redhat-rpm-config
fi
yum install python-devel -y
 
py26=$(python -V 2>&1|grep '2.6.')
if [ "$py26" != "" ];then
    if [ ! -f /etc/yum.repos.d/epel.repo ];then
        wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
    fi
    if [ ! -f /usr/bin/python3 ];then
        yum install python34 python34-devel -y
        if [ ! -f /usr/bin/python3 ];then
            echo "python3.4 install error!"
            exit 0;
        fi
        isSed=$(cat /usr/bin/yum|grep /usr/bin/python2.6)
        if [ "$isSed" == "" ];then
            sed -i "s#/usr/bin/python#/usr/bin/python2.6#" /usr/bin/yum
        fi
        #rm -f /usr/bin/python2
        mv -f /usr/bin/python /usr/bin/python2_backup
        ln -sf /usr/bin/python3 /usr/bin/python
    fi
    if [ ! -f /usr/bin/pip3 ];then
        wget --no-check-certificate https://bootstrap.pypa.io/get-pip.py
        python3 get-pip.py
        mv -f /usr/bin/pip /usr/bin/pip_backup
        ln -sf /usr/bin/pip3.4 /usr/bin/pip
    fi
fi
　　
awkhttps://www.cnblogs.com/ginvip/p/6352157.html
 
打印字段分割符
?
awk -F ":" '{print FS}' /etc/passwd
:
:
打印字段数量
?
awk -F ":" '{print NF}' /etc/passwd
7
7
打印记录的行数
?
awk '{print NR}' /etc/passwd
1
2
3
　　加上说明进行打印  ； \t  Tab键
?
[root@localhost ~]# awk -F":" '{ print "username: " $1 "\t\tuid:" $3 }' /etc/passwd
username: root      uid:0
username: bin       uid:1
　　
?
awk -F ":" '{if(NR>=20 && NR<=30) print $1}' /etc/passwd
tss
postfix
　　
 从该文件中过滤出'Poe'字符串与33794712，最后输出的结果为：Poe 33794712
?
[root@localhost ~]# cat test.txt 
I am Poe,my qq is 33794712
 
[root@localhost ~]# awk -F '[ ,]+' '{print $3" "$7}' test.txt
Poe 33794712
　　
 
?
awk 'BEGIN{info="this is a test";split(info,tA," ");print length(tA);for(k in tA){print k,tA[k];}}'
4    #length(tA) tA数组的长度
4 test    #下标为4的值
1 this
2 is
3 a<br>#分割 info,动态创建数组 tA,awk for …in 循环，是一个无序的循环。 并不是从数组下标
　　
 
?
++s[$NF]   <br>#y[x]定义一个数组s，<br>下标的名称设置为最后一列（$NF），<br>++ 以最后一列（$NF）为标准计数，遇到一个加一，最后将统计出的数字赋值给[键或者说是下标名称，这里是最后一列的名称]<br>#总结：以最后一列分类统计。键为最后一列的名称，值为最后一列出现的次数。
?
netstat -an|awk '/^tcp/{++s[$NF]}END{for(a in s)print a,s[a]}'
　　
?
[root@localhost nginx]# awk 'BEGIN{citie[1]="beijin"} {print citie[1]}' /etc/hosts
beijin
beijin
beijin
 
?
[root@localhost nginx]# awk 'BEGIN{citie[1]="beijin"} END{print citie[1]}' /etc/hosts
beijin
　　
?
[root@localhost nginx]# awk 'BEGIN{citie[1]="beijin"} {print "a"} END{print citie[1]}' /etc/hosts
a
a
a
beijin
　　
 
 