shell基础回顾

Shell脚本

通俗地说，脚本是命令的集合。比如我们把如下命令放到一个文件里：
cd /work11/mywork;
ls;
mkdir aaa;
cd aaa;
那么这个文件就可以说是一个脚本。

shell脚本常用命令

命令语法
if    条件执行 if   条件 then 指令
fi
case 分支执行 case   字符串变量   in
值1) 指令......
值2) 指令......
...
esac
while 条件为真时循环 do
    指令......
   done
until 条件为假时循环   until 条件
   do
    指令......
   done

   for   变量在表中时循环 for 变量名   in    字组表
   do
指令......
done
test   条件测试，语法 test [选项] 参数选项：
-f 文件存在
-gt greater than
-ge greater equal
-lt   lower than
-le lower equal

shell脚本示例 (条件-if）

#!/usr/bin/ksh
If [ $# -ne 1 ]
then
echo “Usage:$0 filename”
exit
else
echo “ok”
fi

file=$1
awk –F”:” ‘{if( substr($2,1,2)==“vc”) printf(“rec=%s\n”,substr($0,index($0,”testPos”)) )}’ $file |head -1 |read val

if [ “X$val” == “X” ]
then
echo val is null!
elif [ $val –gt 3 ]
then
echo val greater than 3.
fi

Shell脚本示例（条件-case）

#!/usr/bin/ksh
param=$1

case $1 in
1)
echo “The param you input is 1”
;;
“xx”)
echo “xxxxxxxxx”
;;
“*”)
echo “The others…”
;;
esac

shell脚本示例（循环-while）

#!/usr/bin/ksh

echo “Continue?(y|n)”
read x

if [ “$x” = “y” –o “$x” = “Y” ]
then
echo “we’ll test the while,pls input”
read y
while [ “$y” != “n” ]
do
  echo “Go on with the while”
  echo “Input pls.”
  read y
done
else
echo “exit”
exit
fi

shell脚本示例（循环-for）

#!/usr/bin/ksh

valList=“aa bb cc dd”

for currVal in ${valList}
do
  case ${currVal } in
  “aa”)
   echo “currVal is aa”
   ;;
  “*)
   if echo $currVal |grep ^bb
   then
    echo “The value starts with bb!\n”
   elif [ `echo $currVal|awk ‘{print substr($0,length($0),1)}’` = “d”
   then
    echo “The value is ended by d”
   else
    echo “Another values”
   fi
   ;;
  esac
done

#!/usr/bin/ksh
. ~/.profile >/dev/null

Shell脚本示例

BINPATH=/bill1/pkg1/bin
BINFILE=bill_backup#这不是unix命令，是我们自定义的程序
CFGPATH=/bill1/pkg1/config/static_backup

if ps -ef|grep -v grep |grep -q ${BINPATH}/${BINFILE}
then
  echo ${BINPATH}/${BINFILE} is alive !
else
  echo ${BINPATH}/${BINFILE} starts running ...
  chmod u+x ${BINPATH}/${BINFILE}

nohup ${BINPATH}/${BINFILE} ${CFGPATH}/static_backup.cfg >/dev/null 2>&1 &
fi

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