幾個簡單的Shell實例親測

#!/bin/bash
a=`ifconfig|grep 'Bcast'| awk {'print $2'}|cut -c 6-`
echo "your PC's IP is "$a
 
2.yes/no返回不同結構（case的應用 ）

 

#!/bin/bash
clear
echo -n "enter [y/n]:"
read a
case $a in
y|Y|Yes|YES|yes) echo "you enter $a";;
n|N|No|no|No) echo "you enter $a";;
*)echo "error";;
esac

 

#!/bin/bash
file="/etc/passwd"
for NUM in 2 4 6 19 13 ;do
echo `sed -n  "$NUM"p  $file`
done

#!/bin/bash
#定義函數
p_num()
{
num=$1
echo $num
}
#使用for循環
for n in $*
do
#把循環到的參數傳遞到函數
p_num $n
done
~

#!/bin/bash
while :
do
echo -n "please input file's name:"
read a
if test -e /home/chensiyao/$a
then
echo "the file is existing.Please input new file name:"
else
mkdir /home/chensiyao/$a
echo "you are sussesfull!"
break
fi
done

#!/bin/sh
# vim: set sw=4 ts=4 et:
help()
{
cat <<HELP
b2h -- convert binary to decimal
USAGE: b2h [-h] binarynum
OPTIONS: -h help text
EXAMPLE: b2h 111010
will return 58
HELP
exit 0
}
error()
{
# print an error and exit
echo "$1"
exit 1
}


lastchar()
{
# is the last num
if [ -z "$1" ];then
rval=""
return
fi
#取當前參數個數，忽略空格
numofchar=`echo -n "$1"|wc -c |sed 's/ //g'`
#取參數最後一個字節
rval=`echo -n "$1"|cut -b $numofchar`
#判斷該值是否為1或0
if [ "$rval" != "1" -a "$rval" != "0" ];then
echo "The number $1 is not a binnumorig!please check!!!"
exit 1
else
return
fi
}

chop()
{
if [ -z "$1" ];then
rval=""
return
fi

#取當前參數個數
numofchar=`echo -n "$1" | wc -c | sed 's/ //g' `

#判斷參數長度是否為1
if [ "$numofchar" = "1" ];then
rval=""
return
fi

#若不為1，則減1，後將rval取參數前(n-1)位
numofcharminus1=`expr $numofchar "-" 1`
rval=`echo -n "$1" |cut -b 0-${numofcharminus1}`

}

#######主程序開始#######

while [ -n "$1" ];do
case $1 in
    -h)help;shift;;
    --)shift;break;;
    -*)error;;
    *)break;;
esac
done


#初始化sum為0，weight為1
sum=0
weight=1

#判斷若參數為空則調用help函數
[ -z "$1" ]&&help

#賦值
binnum="$1"
binnumorig="$1"

#開啟循環，若參數不為空，循環
while [ -n "$binnum" ];do
    #調函數lastchar,返回參數最後一個字節
    lastchar "$binnum"

    #若最後一個字節為1
    if [ "$rval"="1" ];then
    sum=`expr "$weight" "+" "$sum"`
    fi

    #循環，返回參數（n-1）位值
    chop "$binnum"

    #將(n-1)的參數賦於binnum
    binnum="$rval"

    #同時weight*2,因為二進制的規律是1,2,4,8...
    weight=`expr "$weight" "*" 2`

    #直到返回的binnum為空，退出
    done

    #打印結果
    echo "binnary $binnumorig is decimal $sum"