【BASH】如何得到用户输入的YES或NO

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问题：

你需要从用户那里得到简单的yes或no的输入，并且你期望做到用户界面的友好，做到能够区分大小写，并且提供用户点击Enter的默认选项。

 

解决方案

如果是简单的行为，可以使用下面这个函数。

#cookbook filename: func_choose

#Let the user make a choice about something and execute code based on

#the answer

#Called like: choose <default (y or n)> <prompt> <yesaction> <no action>

#e.g. choose "y" /

# "Do you want to play a game?" /

# /usr/games/GlobalThermonucularWar /

# 'printf "%b" "See you later Professor Falkin."'>&2

#Returns: nothing

functionchoose {

localdefault="$1"

localprompt="$2"

localchoice_yes="$3"

localchoice_no="$4"

localanswer

read-p "$prompt" answer

[-z "$answer" ] && answer="$default"

case"$answer" in

[yY1]) exec "$choice_yes"

#error check

;;

[nN0]) exec "$choice_no"

#error check

;;

* ) printf "%b" "Unexpected answer '$answer'!" >&2 ;;

esac

}# end of function choose

 

如果是复杂的操作，可以使用下面的函数

#cookbook filename: func_choice.1

#Let the user make a choice about something and return a standardized

#answer. How the default is handled and what happens next is up to

#the if/then after the choice in main

#Called like: choice <promtp>

#e.g. choice "Do you want to play a game?"

$Returns: global variable CHOICE

functionchoice {

CHOICE=''

localprompt="$*"

localanswer

read-p "$prompt" answer

case"$answer" in

[yY1]) CHOICE='y';;

[nN0]) CHOICE='n';;

* ) CHOICE="$answer";;

esac

}# end of function choice

 

下面这段代码调用choice函数，提示用户确认时间。假设$THISPACKAGE已经设定，将显示时间并要求用户确认，如果用户选择y，Y，或者Enter，那么这个时间就被接受，如果用户输入一个新的时间，函数将循环并且要求用户确认。

#cookbook filename: func_choice.2

until[ "$CHOICE" = "y" ]; do

printf"%b" "This package's date is $THISPACKAGE/n" >&2

choice"Is that correct? [Y/,<New date>]: "

if[ -z "$CHOICE" ]; then

CHOICE='y'

elif[ "$CHOICE" != "y" ]; then

printf"%b" "Overriding $THISPACKAGEwith ${CHOICE}/n"

THISPACKAGE=$CHOICE

fi

done

#Build the package here

 

接下来，使用其他方法来解决这个问题。用户通过认真阅读提示和查看默认行为，可以简单的点击Enter，脚本将执行默认操作。

#If the user types anything except a case insensitive 'n', they will

#see the error log

choice"Do you want to look at the error log file? [Y/n]: "

if[ "$choice" != "n" ]; then

lesserror.log

fi

#If the user types anything except a case insensitive 'y', they will

#not see the message log

choice"Do you want to look at the message log file? [y/N]: "

if[ "$choice" = "y" ]; then

lessmessage.log

fi

最后，如果用户没有输入，可以使用下面的方法解决

#cookbook filename: func_choice.3

choice"Enter your favorite color, if you have one: "

if[ -n "$CHOICE" ]; then

printf"%b" "You chose: $CHOICE"

else

printf"%b" "You do not have a favorite color."

fi