#!/bin/bash
while [ "$1" ]
do
    if [ "$1"="-i" ]
    then
        infile="$2"
        echo $infile
        shift 2
        echo $infile
    elif [ "$1"="-o" ]
    then
        outfile=$2
        echo $outfile
        shift 2
        echo $outfile
    else
        echo "Program $0 doesn't recognize option $1 "
    fi
done
echo $infile
echo $outfile
tr a-z A-Z  $outfile
#end

保存为upcase.
#./upcase -i a.txt -o d.txt |cat -n的时候显示如下：
1.a.txt
2.a.txt
3.d.txt
4.d.txt
5.d.txt
6.
不知道怎么回事，应该是infile变成了d.txt,outfile变成空了。

#cat a.txt
topic.CSDN.net

#cat test.sh

#!/bin/bash
while [ "$1" ]; do
    if [ "$1" == "-i" ]; then
        infile="$2"
        echo $infile
        shift 2
        echo $infile
    elif [ "$1" == "-o" ]; then
        outfile=$2
        echo $outfile
        shift 2
        echo $outfile
    else
        echo "Program $0 doesn't recognize option $1 "
    fi
done
echo $infile
echo $outfile
tr '[a-z]' '[A-Z]' $outfile

#./test.sh -i a.txt -o d.txt
a.txt
a.txt
d.txt
d.txt
a.txt
d.txt

#cat d.txt
TOPIC.CSDN.NET

直接用tr 命令不行吗

tr '[:lower:]' '[:upper:]'  newfile

转换yourfile中的小写字母，转换结果写入文件newfile

tr 'a-z' 'A-Z' 试试