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如何修复差异脚本周围的副作用？

tag-icon • tag-icon command-line bash scripts
如何修复差异脚本周围的副作用？

使用 Ubuntu 20.04.4 LTS (Focal Fossa) 和 diff (GNU diffutils) 3.7

历史：
如何捕获和重用不同的结果？

在测试下面的脚本时...通过 将文件名中的一个字母从 abc.txt 更改为 Abc.txt 大写 A，
使两个目录变得不同。

脚本运行并显示：

diff -rq src1/ dest/  Differences were found. ________________________________________ dirs differ

脚本是：

src1='/media/u3/usb_stick' ; dest='/home/u3/Music/x' ;   
diff -rq "$src1/" "$dest/" ; 
if [ $? -eq 0 ] ; # testing exit status ( 0 <--> match ) No differences echo $? = exit code = 0 ; 
then
 match21=true ; 
else
 match21=false ; 
fi ; 
echo ; 
if $match21 ; 
then
 tput setaf 12 ; echo "diff -rq "src1/" "dest/" " |tr '\n' ' ' ; 
 tput sgr0     ; echo "Match.  Same inputs.  All ok.  No difference.  Success. " ; 
else
 echo "diff -rq "src1/" "dest/"  Differences were found. ________________________________________ dirs differ" ; 
fi ;

但是接下来会出现一个问题...
当 diff 命令被注释掉时#
结果不正确：

diff -rq src1/ dest/  Match.  Same inputs.  All ok.  No difference.  Success.

以上结果不正确。

注释掉的#脚本是

src1='/media/u3/usb_stick' ; dest='/home/u3/Music/x' ; 
# diff -rq "$src1/" "$dest/" ; 
if [ $? -eq 0 ] ; # testing exit status ( 0 <--> match ) No differences echo $? = exit code = 0 ; 
then
 match21=true ; 
else
 match21=false ; 
fi ; 
echo ; 
if $match21 ; 
then
 tput setaf 12 ; echo "diff -rq "src1/" "dest/" " |tr '\n' ' ' ; 
 tput sgr0     ; echo "Match.  Same inputs.  All ok.  No difference.  Success. " ; 
else
 echo "diff -rq "src1/" "dest/"  Differences were found. ________________________________________ dirs differ" ; 
fi ;

如何修复差异脚本周围的副作用？

这意味着当不运行 diff 时，注释掉 #

# diff -rq "$src1/" "$dest/" ;

然后就没有消息或
显示减号，一个填充符：

-

作为一条消息。

答案1

src1='/media/u3/usb_stick' ; 目标='/home/u3/Music/x' ;
# diff -rq "$src1/" "$dest/" ;
如果 [ $?-eq 0 ] ...

这里你检查$?设置后$dest=> $? 是否为0，除非出现错误。
所以这不是“副作用”。

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