bash 循环遍历所有具有特定扩展名的文件
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Loop through all the files with a specific extension
提问by AR89
for i in $(ls);do
if [ $i = '*.java' ];then
echo "I do something with the file $i"
fi
done
I want to loop through each file in the current folder and check if it matches a specific extension. The code above doesn't work, do you know why?
我想遍历当前文件夹中的每个文件并检查它是否与特定扩展名匹配。上面的代码不起作用，你知道为什么吗？
回答by chepner
No fancy tricks needed:
不需要花哨的技巧：
for i in *.java; do
[ -f "$i" ] || break
...
done
The guard ensures that if there are no matching files, the loop will exit without trying to process a non-existent file name *.java. In bash(or shells supporting something similar), you can use the nullgloboption
to simply ignore a failed match and not enter the body of the loop.
守卫确保如果没有匹配的文件，循环将退出而不尝试处理不存在的文件名*.java。在bash（或支持类似内容的 shell）中，您可以使用该nullglob选项来简单地忽略失败的匹配而不进入循环体。
shopt -s nullglob
for i in *.java; do
...
done
回答by uml?ute
the correct answer is @chepner's
正确答案是@chepner
EXT=java
for i in *.${EXT}; do
...
done
however, here's a small trick to check whether a filename has a given extensions:
但是，这里有一个小技巧来检查文件名是否具有给定的扩展名：
EXT=java
for i in *; do
if [ "${i}" != "${i%.${EXT}}" ];then
echo "I do something with the file $i"
fi
done
回答by luismartingil
Recursively add subfolders,
递归添加子文件夹，
for i in `find . -name "*.java" -type f`; do
echo "$i"
done
回答by Benny
Loop through all files ending with: .img, .bin, .txtsuffix, and print the file name:
遍历所有以: .img, .bin,.txt后缀结尾的文件，并打印文件名：
for i in *.img *.bin *.txt;
do
echo "$i"
done
Or in a recursive manner (find also in all subdirectories):
或者以递归方式（也在所有子目录中找到）：
for i in `find . -type f -name "*.img" -o -name "*.bin" -o -name "*.txt"`;
do
echo "$i"
done
回答by user000001
I agree withe the other answers regarding the correct way to loop through the files. However the OP asked:
我同意其他关于正确循环文件方式的答案。然而 OP 问道：
The code above doesn't work, do you know why?
上面的代码不起作用，你知道为什么吗？
Yes!
是的！
An excellent article What is the difference between test, [ and [[ ?] explains in detail that among other differences, you cannot use expression matchingor pattern matchingwithin the testcommand (which is shorthand for [)
一篇很棒的文章test, [ 和 [[ ?] 之间有什么区别，详细解释了在其他区别中，您不能在命令中使用expression matching或（这是 的简写）pattern matchingtest[
Feature new test [[ old test [ Example Pattern matching = (or ==) (not available) [[ $name = a* ]] || echo "name does not start with an 'a': $name" Regular Expression =~ (not available) [[ $(date) =~ ^Fri\ ...\ 13 ]] && echo "It's Friday the 13th!" matching
So this is the reason your script fails. If the OP is interested in an answer with the [[syntax (which has the disadvantage of not being supported on as many platforms as the [command), I would be happy to edit my answer to include it.
所以这就是你的脚本失败的原因。如果 OP 对使用[[语法的答案感兴趣（它的缺点是不受与[命令一样多的平台支持），我很乐意编辑我的答案以包含它。
EDIT: Any protips for how to format the data in the answer as a table would be helpful!
编辑：有关如何将答案中的数据格式化为表格的任何提示都会有所帮助！
回答by peteches
as @chepner says in his comment you are comparing $i to a fixed string.
正如@chepner 在他的评论中所说，您将 $i 与固定字符串进行比较。
To expand and rectify the situation you should use [[ ]] with the regex operator =~
要扩展和纠正这种情况，您应该使用 [[ ]] 和正则表达式运算符 =~
eg:
例如：
for i in $(ls);do
if [[ $i =~ .*\.java$ ]];then
echo "I want to do something with the file $i"
fi
done
the regex to the right of =~ is tested against the value of the left hand operator and should not be quoted, ( quoted will not error but will compare against a fixed string and so will most likely fail"
=~ 右侧的正则表达式针对左侧运算符的值进行测试，不应引用，（引用不会出错，但会与固定字符串进行比较，因此很可能会失败”
but @chepner 's answer above using glob is a much more efficient mechanism.
但是@chepner 上面使用 glob 的回答是一种更有效的机制。
回答by f0nzie
I found this solution to be quite handy. It uses the -oroption in find:
我发现这个解决方案非常方便。它使用以下-or选项find：
find . -name \*.tex -or -name "*.png" -or -name "*.pdf"
find . -name \*.tex -or -name "*.png" -or -name "*.pdf"
It will find the files with extension tex, png, and pdf.
它会找到的文件扩展名为tex，png和pdf。
