如何在 bash 中运行命令直到成功
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How can you run a command in bash over until success
提问by J V
I have a script and want to ask the user for some information, the script cannot continue until the user fills in this information. The following is my attempt at putting a command into a loop to achieve this but it doesn't work for some reason.
我有一个脚本，想向用户询问一些信息，在用户填写这些信息之前，脚本无法继续。以下是我将命令放入循环以实现此目的的尝试，但由于某种原因它不起作用。
echo "Please change password"
while passwd
do
echo "Try again"
done
I have tried many variations of the while loop:
我已经尝试了 while 循环的许多变体：
while `passwd`
while [[ "`passwd`" -gt 0 ]]
while [ `passwd` -ne 0 ]]
# ... And much more
But I can't seem to get it to work.
但我似乎无法让它发挥作用。
回答by Erik
until passwd
do
echo "Try again"
done
or
或者
while ! passwd
do
echo "Try again"
done
回答by Marc B
You need to test $?instead, which is the exit status of the previous command. passwdexits with 0 if everything worked ok, and non-zero if the passwd change failed (wrong password, password mismatch, etc...)
您需要改为测试$?，这是上一个命令的退出状态。passwd如果一切正常，则以 0 退出，如果 passwd 更改失败（密码错误、密码不匹配等），则以非零退出
passwd
while [ $? -ne 0 ]; do
passwd
done
With your backtick version, you're comparing passwd's output, which would be stuff like Enter passwordand confirm passwordand the like.
有了您的反引号的版本，你要比较passwd文件的输出，这将是这样的东西Enter password和confirm password等。
回答by duckworthd
To elaborate on @Marc B's answer,
详细说明@Marc B的回答，
$ passwd
$ while [ $? -ne 0 ]; do !!; done
Is nice way of doing the same thing that's not command specific.
是做同样的事情的好方法，而不是特定于命令的。
回答by kurumi
You can use an infinite loop to achieve this:
您可以使用无限循环来实现此目的：
while true
do
read -p "Enter password" passwd
case "$passwd" in
<some good condition> ) break;;
esac
done
回答by aclokay
If anyone looking to have retry limit:
如果有人希望有重试限制：
max_retry=5
counter=0
until $command
do
sleep 1
[[ counter -eq $max_retry ]] && echo "Failed!" && exit 1
echo "Trying again. Try #$counter"
((counter++))
done
回答by Andrés Rivas
while [ -n $(passwd) ]; do
echo "Try again";
done;
