循环查找文件位置，直到文件存在于bash中 [英] loop for file location until file exists in bash

问题描述

我已经创建了此功能:

function promptFile()

{

while true;
    do
            read -p "Please provide a full path [q to quit]: " file
            if [ $file == q ]; then
                    echo "Exiting.."
                    return 1
            fi

            if [ ! -f $file ]; then
                    echo "File does not exist, please try again"

            else
                    echo $file
                    break
            fi
    done
}

要提示用户输入文件位置，请再次询问文件是否不存在，然后将输出保存到变量中(如果存在)，该函数称为:

To prompt a user for file location, ask again if file does not exist, and save the output to a variable if it does, the function is called:

tempLoc=$(promptFile)
if [ !tempLoc ]; then
        fileLocation=$tempLoc
fi

一切正常，除非有人写了错误的文件位置，否则直到有人单击q或输入现有文件位置后，回显才会显示. 在这种情况下，将显示回显消息*错误输入的数量，如下所示.

Everything works well unless someone write a bad file location, then the echo is not shown until someone clicks q or inputs an existing file location. in which case the echo message will be printed * the number of bad inputs, as follows.

[root@tsting:0]# ./tst
Please provide a full path [q to quit]: tst1
Please provide a full path [q to quit]: tst2
Please provide a full path [q to quit]: tst3
Please provide a full path [q to quit]: tst4
Please provide a full path [q to quit]: q
File does not exist File does not exist File does not exist File does not exist Exiting..
[root@tsting:0]#

我猜这是因为循环崩溃了，它会在发生所有回声时回退打印，有没有一种方法可以避免这种情况，只在输入错误的文件位置时才打印回声?

I'm guessing this happens because the loop collapses back printing all the echos as it happens, is there a way to avoid this and just print the echo when the wrong file location is entered ?

推荐答案

将错误写入stderr

Write the error to stderr

echo "File does not exist, please try again" >&2

您会将函数的所有输出保存到变量tempLoc中，因此，即使用户输入了有效文件，该变量也会在其中带有大量垃圾.

You are saving all output from the function into the variable tempLoc, so even if the user inputs a valid file it will have a load of junk in the variable with it.

无论如何，Stderr还是应该出现错误消息的地方，因此，即使没有这个问题，将错误消息发送到那里也是一个好习惯.

Stderr is where error messages should go anyway though, so it's good practice to send them there even without this problem.

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