I want to pause input in a shell script, and prompt the user for choices. The standard 'Yes, No, or Cancel' type question. How do I accomplish this in a typical bash prompt?
echo "Please enter some input: "
read input_variable
echo "You entered: $input_variable"
inquire () {
echo -n "$1 [y/n]? "
read answer
finish="-1"
while [ "$finish" = '-1' ]
do
finish="1"
if [ "$answer" = '' ];
then
answer=""
else
case $answer in
y | Y | yes | YES ) answer="y";;
n | N | no | NO ) answer="n";;
*) finish="-1";
echo -n 'Invalid response -- please reenter:';
read answer;;
esac
fi
done
}
... other stuff
inquire "Install now?"
...
The simplest and most widely available method to get user input at a shell prompt is the read command. The best way to illustrate its use is a simple demonstration:
while true; do
read -p "Do you wish to install this program?" yn
case $yn in
[Yy]* ) make install; break;;
[Nn]* ) exit;;
* ) echo "Please answer yes or no.";;
esac
done
Another method, pointed out by Steven Huwig, is Bash's select command. Here is the same example using select:
echo "Do you wish to install this program?"
select yn in "Yes" "No"; do
case $yn in
Yes ) make install; break;;
No ) exit;;
esac
done
With select you don't need to sanitize the input – it displays the available choices, and you type a number corresponding to your choice. It also loops automatically, so there's no need for a while true loop to retry if they give invalid input.
Also, please check out the excellent answer by F. Hauri.
I suggest you use dialog...
Linux Apprentice: Improve Bash Shell Scripts Using Dialog
The dialog command enables the use of window boxes in shell scripts to make their use more interactive.
it's simple and easy to use, there's also a gnome version called gdialog that takes the exact same parameters, but shows it GUI style on X.
Bash has select for this purpose.
select result in Yes No Cancel
do
echo $result
done
read -p "Are you alright? (y/n) " RESP
if [ "$RESP" = "y" ]; then
echo "Glad to hear it"
else
echo "You need more bash programming"
fi
You can use the built-in read command ; Use the -p option to prompt the user with a question.
Since BASH4, you can now use -i to suggest an answer, so the user only have to press return to enter it :
read -e -p "Enter the path to the file: " -i "/usr/local/etc/" FILEPATH
echo $FILEPATH
(But remember to use the "readline" option -e to allow line editing with arrow keys)
If you want a "yes / no" logic, you can do something like this:
read -e -p "
List the content of your home dir ? [Y/n] " YN
[[ $YN == "y" || $YN == "Y" || $YN == "" ]] && ls -la ~/
Use the read command:
echo Would you like to install? "(Y or N)"
read x
# now check if $x is "y"
if [ "$x" = "y" ]; then
# do something here!
fi
and then all of the other stuff you need
Here's something I put together:
#!/bin/sh
promptyn () {
while true; do
read -p "$1 " yn
case $yn in
[Yy]* ) return 0;;
[Nn]* ) return 1;;
* ) echo "Please answer yes or no.";;
esac
done
}
if promptyn "is the sky blue?"; then
echo "yes"
else
echo "no"
fi
I'm a beginner, so take this with a grain of salt, but it seems to work.
yn() {
if [[ 'y' == `read -s -n 1 -p "[y/n]: " Y; echo $Y` ]];
then eval $1;
else eval $2;
fi }
yn 'echo yes' 'echo no'
yn 'echo absent no function works too!'
This solution reads a single character and calls a function on a yes response.
read -p "Are you sure? (y/n) " -n 1
echo
if [[ $REPLY =~ ^[Yy]$ ]]; then
do_something
fi
Multiple choice version:
ask () { # $1=question $2=options
# set REPLY
# options: x=..|y=..
while $(true); do
printf '%s [%s] ' "$1" "$2"
stty cbreak
REPLY=$(dd if=/dev/tty bs=1 count=1 2> /dev/null)
stty -cbreak
test "$REPLY" != "$(printf '\n')" && printf '\n'
(
IFS='|'
for o in $2; do
if [ "$REPLY" = "${o%%=*}" ]; then
printf '\n'
break
fi
done
) | grep ^ > /dev/null && return
done
}
Example:
$ ask 'continue?' 'y=yes|n=no|m=maybe'
continue? [y=yes|n=no|m=maybe] g
continue? [y=yes|n=no|m=maybe] k
continue? [y=yes|n=no|m=maybe] y
$
It will set REPLY to y (inside the script).
To get a nice ncurses-like inputbox use the command dialog like this:
#!/bin/bash
if (dialog --title "Message" --yesno "Want to do something risky?" 6 25)
# message box will have the size 25x6 characters
then
echo "Let's do something risky"
# do something risky
else
echo "Let's stay boring"
fi
The dialog package is installed by default at least with SUSE Linux.
Sorry for posting on such an old post. Some weeks ago I was facing a similar problem, in my case I needed a solution which also worked within an online installer-script, eg: curl -Ss https://raw.github.com/_____/installer.sh | bash
Using read yesno < /dev/tty works fine for me:
echo -n "These files will be uploaded. Is this ok? (y/n) "
read yesno < /dev/tty
if [ "x$yesno" = "xy" ];then
# Yes
else
# No
fi
Hope this helps someone.
Inspired by the answers of @Mark and @Myrddin I created this function for a universal prompt
uniprompt(){
while true; do
echo -e "$1\c"
read opt
array=($2)
case "${array[@]}" in *"$opt"*) eval "$3=$opt";return 0;; esac
echo -e "$opt is not a correct value\n"
done
}
use it like this:
unipromtp "Select an option: (a)-Do one (x)->Do two (f)->Do three : " "a x f" selection
echo "$selection"
Depending on
and if you want
You could use the read command, followed by if ... then ... else:
echo -n "Is this a good question (y/n)? "
read answer
# if echo "$answer" | grep -iq "^y" ;then
if [ "$answer" != "${answer#[Yy]}" ] ;then
echo Yes
else
echo No
fi
(Thanks to Adam Katz's comment: Replaced the test above with one that is more portable and avoids one fork:)
But if you don't want the user to have to hit Return, you could write:
(Edited: As @JonathanLeffler rightly suggest, saving stty's configuration could be better than simply force them to sane.)
echo -n "Is this a good question (y/n)? "
old_stty_cfg=$(stty -g)
stty raw -echo ; answer=$(head -c 1) ; stty $old_stty_cfg # Careful playing with stty
if echo "$answer" | grep -iq "^y" ;then
echo Yes
else
echo No
fi
Note: This was tested under sh, bash, ksh, dash and busybox!
Same, but waiting explicitly for y or n:
#/bin/sh
echo -n "Is this a good question (y/n)? "
old_stty_cfg=$(stty -g)
stty raw -echo
answer=$( while ! head -c 1 | grep -i '[ny]' ;do true ;done )
stty $old_stty_cfg
if echo "$answer" | grep -iq "^y" ;then
echo Yes
else
echo No
fi
There are many tools which were built using libncurses, libgtk, libqt or other graphical libraries. For example, using whiptail:
if whiptail --yesno "Is this a good question" 20 60 ;then
echo Yes
else
echo No
fi
Depending on your system, you may need to replace whiptail with another similiar tool:
dialog --yesno "Is this a good question" 20 60 && echo Yes
gdialog --yesno "Is this a good question" 20 60 && echo Yes
kdialog --yesno "Is this a good question" 20 60 && echo Yes
where 20 is height of dialog box in number of lines and 60 is width of the dialog box. These tools all have near same syntax.
DIALOG=whiptail
if [ -x /usr/bin/gdialog ] ;then DIALOG=gdialog ; fi
if [ -x /usr/bin/xdialog ] ;then DIALOG=xdialog ; fi
...
$DIALOG --yesno ...
read -p "Is this a good question (y/n)? " answer
case ${answer:0:1} in
y|Y )
echo Yes
;;
* )
echo No
;;
esac
I prefer to use case so I could even test for yes | ja | si | oui if needed...
Under bash, we can specify the length of intended input for for the read command:
read -n 1 -p "Is this a good question (y/n)? " answer
Under bash, read command accepts a timeout parameter, which could be useful.
read -t 3 -n 1 -p "Is this a good question (y/n)? " answer
[ -z "$answer" ] && answer="Yes" # if 'yes' have to be default choice
More sophisticated dialog boxes, beyond simple yes - no purposes:
dialog --menu "Is this a good question" 20 60 12 y Yes n No m Maybe
Progress bar:
dialog --gauge "Filling the tank" 20 60 0 < <(
for i in {1..100};do
printf "XXX\n%d\n%(%a %b %T)T progress: %d\nXXX\n" $i -1 $i
sleep .033
done
)
Little demo:
#!/bin/sh
while true ;do
[ -x "$(which ${DIALOG%% *})" ] || DIALOG=dialog
DIALOG=$($DIALOG --menu "Which tool for next run?" 20 60 12 2>&1 \
whiptail "dialog boxes from shell scripts" >/dev/tty \
dialog "dialog boxes from shell with ncurses" \
gdialog "dialog boxes from shell with Gtk" \
kdialog "dialog boxes from shell with Kde" ) || exit
clear;echo "Choosed: $DIALOG."
for i in `seq 1 100`;do
date +"`printf "XXX\n%d\n%%a %%b %%T progress: %d\nXXX\n" $i $i`"
sleep .0125
done | $DIALOG --gauge "Filling the tank" 20 60 0
$DIALOG --infobox "This is a simple info box\n\nNo action required" 20 60
sleep 3
if $DIALOG --yesno "Do you like this demo?" 20 60 ;then
AnsYesNo=Yes; else AnsYesNo=No; fi
AnsInput=$($DIALOG --inputbox "A text:" 20 60 "Text here..." 2>&1 >/dev/tty)
AnsPass=$($DIALOG --passwordbox "A secret:" 20 60 "First..." 2>&1 >/dev/tty)
$DIALOG --textbox /etc/motd 20 60
AnsCkLst=$($DIALOG --checklist "Check some..." 20 60 12 \
Correct "This demo is useful" off \
Fun "This demo is nice" off \
Strong "This demo is complex" on 2>&1 >/dev/tty)
AnsRadio=$($DIALOG --radiolist "I will:" 20 60 12 \
" -1" "Downgrade this answer" off \
" 0" "Not do anything" on \
" +1" "Upgrade this anser" off 2>&1 >/dev/tty)
out="Your answers:\nLike: $AnsYesNo\nInput: $AnsInput\nSecret: $AnsPass"
$DIALOG --msgbox "$out\nAttribs: $AnsCkLst\nNote: $AnsRadio" 20 60
done
More sample? Have a look at Using whiptail for choosing USB device and USB removable storage selector: USBKeyChooser
Example:
#!/bin/bash
set -i
HISTFILE=~/.myscript.history
history -c
history -r
myread() {
read -e -p '> ' $1
history -s ${!1}
}
trap 'history -a;exit' 0 1 2 3 6
while myread line;do
case ${line%% *} in
exit ) break ;;
* ) echo "Doing something with '$line'" ;;
esac
done
This will create a file .myscript.history in your $HOME directory, than you could use readline's history commands, like Up, Down, Ctrl+r and others.
One simple way to do this is with xargs -p or gnu parallel --interactive.
I like the behavior of xargs a little better for this because it executes each command immediately after the prompt like other interactive unix commands, rather than collecting the yesses to run at the end. (You can Ctrl-C after you get through the ones you wanted.)
e.g.,
echo *.xml | xargs -p -n 1 -J {} mv {} backup/
read -e -p "Enter your choice: " choice
The -e option enables the user to edit the input using arrow keys.
If you want to use a suggestion as input:
read -e -i "yes" -p "Enter your choice: " choice
-i option prints a suggestive input.
As a friend of a one line command I used the following:
while [ -z $prompt ]; do read -p "Continue (y/n)?" choice;case "$choice" in y|Y ) prompt=true; break;; n|N ) exit 0;; esac; done; prompt=;
Written longform, it works like this:
while [ -z $prompt ];
do read -p "Continue (y/n)?" choice;
case "$choice" in
y|Y ) prompt=true; break;;
n|N ) exit 0;;
esac;
done;
prompt=;
more generic would be:
function menu(){
title="Question time"
prompt="Select:"
options=("Yes" "No" "Maybe")
echo "$title"
PS3="$prompt"
select opt in "${options[@]}" "Quit/Cancel"; do
case "$REPLY" in
1 ) echo "You picked $opt which is option $REPLY";;
2 ) echo "You picked $opt which is option $REPLY";;
3 ) echo "You picked $opt which is option $REPLY";;
$(( ${#options[@]}+1 )) ) clear; echo "Goodbye!"; exit;;
*) echo "Invalid option. Try another one.";continue;;
esac
done
return
}
do_xxxx=y # In batch mode => Default is Yes
[[ -t 0 ]] && # If TTY => Prompt the question
read -n 1 -p $'\e[1;32m
Do xxxx? (Y/n)\e[0m ' do_xxxx # Store the answer in $do_xxxx
if [[ $do_xxxx =~ ^(y|Y|)$ ]] # Do if 'y' or 'Y' or empty
then
xxxx
fi
[[ -t 0 ]] && read ... => Call command read if TTYread -n 1 => Wait for one character$'\e[1;32m ... \e[0m ' => Print in green[[ $do_xxxx =~ ^(y|Y|)$ ]] => bash regexdo_xxxx=y
[[ -t 0 ]] && { # Timeout 5 seconds (read -t 5)
read -t 5 -n 1 -p $'\e[1;32m
Do xxxx? (Y/n)\e[0m ' do_xxxx || # read 'fails' on timeout
do_xxxx=n ; } # Timeout => answer No
if [[ $do_xxxx =~ ^(y|Y|)$ ]]
then
xxxx
fi
The easiest way to achieve this with the least number of lines is as follows:
read -p "<Your Friendly Message here> : y/n/cancel" CONDITION;
if [ "$CONDITION" == "y" ]; then
# do something here!
fi
The if is just an example: it is up to you how to handle this variable.
I've used the case statement a couple of times in such a scenario, using the case statment is a good way to go about it. A while loop, that ecapsulates the case block, that utilizes a boolean condition can be implemented in order to hold even more control of the program, and fulfill many other requirements. After the all the conditions have been met, a break can be used which will pass control back to the main part of the program. Also, to meet other conditions, of course conditional statements can be added to accompany the control structures: case statement and possible while loop.
Example of using a case statement to fulfill your request
#! /bin/sh
# For potential users of BSD, or other systems who do not
# have a bash binary located in /bin the script will be directed to
# a bourne-shell, e.g. /bin/sh
# NOTE: It would seem best for handling user entry errors or
# exceptions, to put the decision required by the input
# of the prompt in a case statement (case control structure),
echo Would you like us to perform the option: "(Y|N)"
read inPut
case $inPut in
# echoing a command encapsulated by
# backticks (``) executes the command
"Y") echo `Do something crazy`
;;
# depending on the scenario, execute the other option
# or leave as default
"N") echo `execute another option`
;;
esac
exit
I noticed that no one posted an answer showing multi-line echo menu for such simple user input so here is my go at it:
#!/bin/bash
function ask_user() {
echo -e "
#~~~~~~~~~~~~#
| 1.) Yes |
| 2.) No |
| 3.) Quit |
#~~~~~~~~~~~~#\n"
read -e -p "Select 1: " choice
if [ "$choice" == "1" ]; then
do_something
elif [ "$choice" == "2" ]; then
do_something_else
elif [ "$choice" == "3" ]; then
clear && exit 0
else
echo "Please select 1, 2, or 3." && sleep 3
clear && ask_user
fi
}
ask_user
This method was posted in the hopes that someone may find it useful and time-saving.
#!/usr/bin/env bash
@confirm() {
local message="$*"
local result=''
echo -n "> $message (Yes/No/Cancel) " >&2
while [ -z "$result" ] ; do
read -s -n 1 choice
case "$choice" in
y|Y ) result='Y' ;;
n|N ) result='N' ;;
c|C ) result='C' ;;
esac
done
echo $result
}
case $(@confirm 'Confirm?') in
Y ) echo "Yes" ;;
N ) echo "No" ;;
C ) echo "Cancel" ;;
esac
#!/usr/bin/env bash
@confirm() {
local message="$*"
local result=3
echo -n "> $message (y/n) " >&2
while [[ $result -gt 1 ]] ; do
read -s -n 1 choice
case "$choice" in
y|Y ) result=0 ;;
n|N ) result=1 ;;
esac
done
return $result
}
if @confirm 'Confirm?' ; then
echo "Yes"
else
echo "No"
fi
In response to others:
You don't need to specify case in BASH4 just use the ',,' to make a var lowercase. Also I strongly dislike putting code inside of the read block, get the result and deal with it outside of the read block IMO. Also include a 'q' for quit IMO. Lastly why type 'yes' just use -n1 and have the press y.
Example: user can press y/n and also q to just quit.
ans=''
while true; do
read -p "So is MikeQ the greatest or what (y/n/q) ?" -n1 ans
case ${ans,,} in
y|n|q) break;;
*) echo "Answer y for yes / n for no or q for quit.";;
esac
done
echo -e "\nAnswer = $ans"
if [[ "${ans,,}" == "q" ]] ; then
echo "OK Quitting, we will assume that he is"
exit 0
fi
if [[ "${ans,,}" == "y" ]] ; then
echo "MikeQ is the greatest!!"
else
echo "No? MikeQ is not the greatest?"
fi
Here's a longer, but reusable and modular approach:
0=yes and 1=nozsh and bash.Note that the N is capitalsed. Here enter is pressed, accepting the default:
$ confirm "Show dangerous command" && echo "rm *"
Show dangerous command [y/N]?
Also note, that [y/N]? was automatically appended. The default "no" is accepted, so nothing is echoed.
Re-prompt until a valid response is given:
$ confirm "Show dangerous command" && echo "rm *"
Show dangerous command [y/N]? X
Show dangerous command [y/N]? y
rm *
Note that the Y is capitalised:
$ confirm_yes "Show dangerous command" && echo "rm *"
Show dangerous command [Y/n]?
rm *
Above, I just pressed enter, so the command ran.
y or n$ get_yes_keypress "Here you cannot press enter. Do you like this [y/n]? "
Here you cannot press enter. Do you like this [y/n]? k
Here you cannot press enter. Do you like this [y/n]?
Here you cannot press enter. Do you like this [y/n]? n
$ echo $?
1
Here, 1 or false was returned. Note that with this lower-level function you'll need to provide your own [y/n]? prompt.
# Read a single char from /dev/tty, prompting with "$*"
# Note: pressing enter will return a null string. Perhaps a version terminated with X and then remove it in caller?
# See https://unix.stackexchange.com/a/367880/143394 for dealing with multi-byte, etc.
function get_keypress {
local REPLY IFS=
>/dev/tty printf '%s' "$*"
[[ $ZSH_VERSION ]] && read -rk1 # Use -u0 to read from STDIN
# See https://unix.stackexchange.com/q/383197/143394 regarding '\n' -> ''
[[ $BASH_VERSION ]] && </dev/tty read -rn1
printf '%s' "$REPLY"
}
# Get a y/n from the user, return yes=0, no=1 enter=$2
# Prompt using $1.
# If set, return $2 on pressing enter, useful for cancel or defualting
function get_yes_keypress {
local prompt="${1:-Are you sure [y/n]? }"
local enter_return=$2
local REPLY
# [[ ! $prompt ]] && prompt="[y/n]? "
while REPLY=$(get_keypress "$prompt"); do
[[ $REPLY ]] && printf '\n' # $REPLY blank if user presses enter
case "$REPLY" in
Y|y) return 0;;
N|n) return 1;;
'') [[ $enter_return ]] && return "$enter_return"
esac
done
}
# Credit: http://unix.stackexchange.com/a/14444/143394
# Prompt to confirm, defaulting to NO on <enter>
# Usage: confirm "Dangerous. Are you sure?" && rm *
function confirm {
local prompt="${*:-Are you sure} [y/N]? "
get_yes_keypress "$prompt" 1
}
# Prompt to confirm, defaulting to YES on <enter>
function confirm_yes {
local prompt="${*:-Are you sure} [Y/n]? "
get_yes_keypress "$prompt" 0
}