Linux：Bash：mkdir 返回什么
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Linux: Bash: what does mkdir return
提问by Tu Hoang
I want to write a simple check upon running mkdir to create a dir. First it will check whether the dir already exists, if it does, it will just skip. If the dir doesn't exist, it will run mkdir, if mkdir fails (meaning the script could not create the dir because it does not have sufficient privileges), it will terminate.
我想在运行 mkdir 以创建目录时编写一个简单的检查。首先它会检查目录是否已经存在，如果存在，它将跳过。如果目录不存在，它将运行 mkdir，如果 mkdir 失败（意味着脚本无法创建目录，因为它没有足够的权限），它将终止。
This is what I wrote:
这是我写的：
if [ ! -d "$FINALPATH" ]; then
if [[ `mkdir -p "$FINALPATH"` -ne 0 ]]; then
echo "\nCannot create folder at $FOLDERPATH. Dying ..."
exit 1
fi
fi
However, the 2nd if doesn't seem to be working right (I am catching 0 as return value for a successful mkdir). So how to correctly write the 2nd if? and what does mkdir returns upon success as well as failure?
但是，第二个 if 似乎无法正常工作（我正在捕获 0 作为成功 mkdir 的返回值）。那么如何正确写出第二个if呢？mkdir 在成功和失败时返回什么？
采纳答案by Owen
The result of running
运行的结果
`mkdir -p "$FINALPATH"`
isn't the return code, but the output from the program. $?the return code. So you could do
不是返回码，而是程序的输出。$?返回码。所以你可以这样做
if mkdir -p "$FINALPATH" ; then
# success
else
echo Failure
fi
or
或者
mkdir -p "$FINALPATH"
if [ $? -ne 0 ] ; then
echo Failure
fi
回答by sehe
The shorter way would be
更短的方法是
mkdir -p "$FINALPATH" || echo failure
also idiomatic:
也是惯用语：
if mkdir -p "$FINALPATH"
then
# .....
fi
Likewise you can while .....; do ....; doneor until ......; do ......; done
同样你可以while .....; do ....; done或until ......; do ......; done
回答by Dr Beco
Just for completeness, you can exit by issuing:
为了完整起见，您可以通过发出以下命令退出：
mkdir -p "$FINALPATH" || { echo "Failure, aborting..." ; exit 1 ; }
Braces are necessary, or else exit 1would execute in both cases.
大括号是必要的，否则exit 1在这两种情况下都会执行。
Or you can create an abort function like:
或者您可以创建一个中止函数，例如：
errormsg()
{
echo ""
echo Aborting...
{ exit 1 ; }
}
And then just call it by issuing:
然后只需通过发出以下命令来调用它：
mkdir -p "$FINALPATH" || errormsg "Failure creating $FINALPATH"
Edited:
编辑：
- Braces, not parenthesis, as parenthesis only exit the subshell. ( Thanks @Charles Duffy )
- A function to write a message and exit
- 大括号，而不是括号，因为括号只退出子外壳。（感谢@Charles Duffy）
- 一个写消息并退出的函数
