bash “~/Desktop/test.txt：没有那个文件或目录”
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"~/Desktop/test.txt: No such file or directory"
提问by Mason
I've written this script:
我写了这个脚本：
#!/bin/bash
file="~/Desktop/test.txt"
echo "TESTING" > $file
The script doesn't work; it gives me this error:
脚本不起作用；它给了我这个错误：
./tester.sh: line 4: ~/Desktop/test.txt: No such file or directory
What am I doing wrong?
我究竟做错了什么？
回答by Michael Hoffman
Try replacing ~with $HOME. Tilde expansion only happens when the tilde is unquoted. See info "(bash) Tilde Expansion".
尝试替换~为$HOME. 波浪号扩展仅在波浪号未加引号时发生。见info "(bash) Tilde Expansion"。
You could also do file=~/Desktopwithout quoting it, but if you ever replace part of this with something with a field separator in it, then it will break. Quoting the values of variables is probably a good thing to get into the habit of anyway. Quoting variable file=~/"Desktop"will also work but I think that is rather ugly.
您也可以file=~/Desktop不引用它，但是如果您将其中的一部分替换为带有字段分隔符的内容，那么它就会损坏。无论如何，引用变量的值可能是养成习惯的一件好事。引用变量file=~/"Desktop"也可以，但我认为这很丑陋。
Another reason to prefer $HOME, when possible: tilde expansion only happens at the beginnings of words. So command --option=~/foowill only work if commanddoes tilde expansion itself, which will vary by command, while command --option="$HOME/foo"will always work.
$HOME在可能的情况下，更喜欢 的另一个原因是：波浪号扩展只发生在单词的开头。所以command --option=~/foo只有command在波浪号扩展本身时才有效，这将因命令而异，而command --option="$HOME/foo"将始终有效。
回答by Sanghyun Lee
FYI, you can also use eval:
仅供参考，您还可以使用eval：
eval "echo "TESTING" > $file"
The evaltakes the command as an argument and it causes the shell to do the Tilde expansion.
在eval作为参数取指令，它会导致壳做波浪线扩展。
