Made a script that the user gives a "parameter" and it prints out if it is a file, directory or non of them. This is it :
#!/bin/bash
read parametros
for filename in *
do
if [ -f "$parametros" ];
then
echo "$parametros is a file"
elif [ -d "$parametros" ];
then
echo "$parametros is a directory"
else
echo " There is not such file or directory"
fi
exit
done
Altough i want the user to be allowed to give only one word as a parameter. How do i make this happen ? (For example if user press space after first word there would be an error message showing "wrong input")
#!/bin/bash
read parametros
if [[ "$parametros" = *[[:space:]]* ]]
then
echo "wrong input"
elif [[ -f "$parametros" ]]
then
echo "$parametros is a file"
elif [[ -d "$parametros" ]]
then
echo "$parametros is a directory"
else
echo " There is not such file or directory"
fi
See http://mywiki.wooledge.org/BashFAQ/031 for the difference between [...] and [[...]].
You have to use the $#. It gives the number of the parameters.
The code will be something like:
if [ "$#" -ne 1 ]; then
printf 'ERROR!\n'
exit 1
fi
First, I'm curious why you want to restrict to one word - a file or directory could have spaces in it, but maybe you are preventing that somehow in your context.
Here are a few ways you could approach it:
Validate the input after they enter it - check if it has any spaces, eg: if [[ "parametros" == *" " ]]; then...
Get one character at a time in a while loop, eg with: read -n1 char
Show an error if it's a space
Break the loop if it's 'enter'
Build up the overall string from the entered characters
1 is obviously much simpler, but maybe 2 is worth the effort for the instant feedback that you are hoping for?
I created a script in bash that checking the strength of a password comibination
I want to add an option that the user can input a password from a text file (The user types -f and then the file path and the he gets a password review ) or he types the password without any option before
What I want to ask what I need to do if I want to use an argument.
Like if the user doesnt use a file in order to read the password from text file
he just type the password by himself
#!/bin/bash
while getopts ":f:" option; do
case $option in
f) password=`cat $OPTARG` ;;
esac
done
#evaluating how much chars the password has
password_length=${#password}
#counter for checking in how much sections the password meets the rquirements
count=0
#Creating an array for stroing reasons why the password is incorrect
requirements=(foo bar)
#Checking if password includes minimum of 10 characters
if [ $password_length -ge 10 ];
then
requirements[0]="Correct"
else
requirements[0]="Incorrect password syntax. The password
length must includes minimum of 10 characters"
fi
#checkig if the password includes both alphabet and number
if [[ "$password" == *[a-zA-Z]* && "$password" == *[0-9]* ]]
then
requirements[1]="Correct"
else
requirements[1]="Incorrect password syntax. The password
must includes both alphabet and number"
fi
#checking if password includes both the small and capital case letters.
if [[ "$password" == *[A-Z]* && "$password" == *[a-z]* ]];
then
requirements[2]="Correct"
else
requirements[2]="Incorrect password syntax. The password
must includes both the small and capital case letters"
fi
#checking whether the password is according to the requirements or not
#if yes count will equal to 3 at the end
for i in "${requirements[#]}"
do
if [[ $i == "Correct" ]];
then
let count++
fi
done
#if the counter count is equal to 3 print the password in light green color and return exit 0
if [[ $count -eq 3 ]];
then
echo -e "\e[92m$password"
# sleep - user has the time to see that the password's syntax is correct
sleep 3
exit 0
#if the count is not equal to 3 print the password in reg color and return exit 1
else
echo -e "\e[91m$password"
for i in "${requirements[#]}"
do
if [[ $i != "Correct" ]];
then
echo $i
fi
done
# sleep - user has the time to see that the password's syntax is incorrect and the reasons for that
sleep 6
exit 1
fi
so what to write in the script for take an argument what the user will type if he doesnt uses an option
Check whether the password variable has already been set. If not, ask the user to enter it.
while getopts ":f:" option; do
case $option in
f) password=`cat $OPTARG` ;;
esac
done
if [ -z "$password" ]
then read -p "Enter password: " -r password
fi
Generally, after a while getopts loop, you want to shift off the options you've just processed:
while getopts ":f:" option; do
case $option in
f) # bash builtin way to slurp a file into a variable
password=$(< "$OPTARG") ;;
esac
done
# remove the options, if any
shift $((OPTIND - 1))
# the remaining command line arguments are at `$1`, `$2`, etc, as usual.
[[ -n $1 ]] && password=$1
What do you want to do if your user specifies both the -f option and gives a password on the command line? Which one do you want to use? With what I've written, the command line password wins.
Another way to implement this, where the -f option takes precedence:
password_file=""
while getopts ":f:" option; do
case $option in
f) password_file=$OPTARG ;;
esac
done
shift $((OPTIND - 1))
if [[ -n $password_file ]]; then
if [[ ! -r $password_file ]]; then
echo "Cannot read '$password_file'" >&2
exit 1
fi
password=$(< "$password_file")
elif [[ -n $1 ]]; then
password=$1
else
echo "No password provided. Usage: ..." >&2
exit 1
fi
This is my Shellscript
echo "IsInteractive"
read IsInteractive
if [ "$IsInteractive" == "true" ]; then
echo "Name"
read name
echo "Password"
read password
if [ "$name" == "abcd" & "$password" == "pwd" ]; then
echo "correct username and password"
else
echo "wrong username or password"
fi
elif [ "$IsInteractive" == "false" ]; then
echo "Everything working fine.But no logic given yet"
else
echo "Give proper input"
fi
Is there something wrong in the 2nd if-condition?I tried putting && in the condition,but didn't work
You don't use multiple condition inside square brackets as &, you use -a. Or you use multiple brackets if [ $a = "a" ] && [ $b = "c" ]
You can also use the case/esac construct , eg
case "$name$password" in
"abcdpwd" ) echo "correct" ;;
*) echo "not correct";;
esac
This is much cleaner than if/else IMO.
Inside square brackets -a is the equivalent to &&
Also, you should probably be using = not ==. Read the manpage for your shell.
if [ "$name" == "abcd" -a "$password" == "pwd" ]; then echo true; else echo false; fi
This and MANY more "basic" questions can be answered quickly and without the need for a forum-post with the command man bash on most systems; and if it's not there just google "man bash" and pick the one which seems closest to your system... they're all "pretty much the same", especially at the basic level.
Cheers. Keith.
EDIT: FWW: the [ ] construct is a short-cut for "test", a function which is built-into all the the "standard" shells (sh, csh, ksh, and bash)... so the following code is EXACTLY equivalent:
$ a=a
$ b=c
$ if test "$a" = "a" && test "$b" = "c"; then echo true; else echo false; fi
true
The if then construct just evaluates the return value from the test function. You can display the return value of your last shell command with $?... but beware, echo also sets $?:
$ true
$ echo $?
0
$ false
$ echo $?
1
$ echo $?
0
The really interesting ramification of that is that the if then construct can evaluate anything which returns success=0=true or failure=anything BUT 0 (typically 1=false)... be that a shell built-in function, a user-defined function, a unix utility or a program you wrote yourself. Hence the following code is roughly equivalent:
$ if echo "$a:$b" | fgrep -s "a:c"; then echo true; else echo false; fi
a:c
true
NOTE: looks like my system's fgrep doesn't accept the -s for silent switch. Sigh.
Note that in above example, where the output from echo is being piped to the standard fgrep utility, it is the return value of fgrep (the LAST command to be invoked) which is evaluated by if then.
Good luck, and may root be with you. Cheers again. Keith.
A minor change will resolve this scripting error [: missing `]'.
At line 8 replace '&' with '-a'
-a, the logical AND. If both the operands are true then condition would be true otherwise it would be false
Working code below
echo "IsInteractive"
read IsInteractive
if [ "$IsInteractive" == "true" ]; then
echo "Name"
read name
echo "Password"
read password
if [ "$name" == "abcd" -a "$password" == "pwd" ]; then
echo "correct username and password"
else
echo "wrong username or password"
fi
elif [ "$IsInteractive" == "false" ]; then
echo "Everything working fine.But no logic given yet"
else
echo "Give proper input"
fi
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?
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, Léa Gris demonstrated a way to make the request language agnostic in her answer. Adapting my first example to better serve multiple languages might look like this:
set -- $(locale LC_MESSAGES)
yesexpr="$1"; noexpr="$2"; yesword="$3"; noword="$4"
while true; do
read -p "Install (${yesword} / ${noword})? " yn
if [[ "$yn" =~ $yesexpr ]]; then make install; exit; fi
if [[ "$yn" =~ $noexpr ]]; then exit; fi
echo "Answer ${yesword} / ${noword}."
done
Obviously other communication strings remain untranslated here (Install, Answer) which would need to be addressed in a more fully completed translation, but even a partial translation would be helpful in many cases.
Finally, please check out the excellent answer by F. Hauri.
At least five answers for one generic question.
Depending on
posix compliant: could work on poor systems with generic shell environments
bash specific: using so called bashisms
and if you want
simple ``in line'' question / answer (generic solutions)
pretty formatted interfaces, like ncurses or more graphical using libgtk or libqt...
use powerful readline history capability
1. POSIX generic solutions
You could use the read command, followed by if ... then ... else:
printf 'Is this a good question (y/n)? '
read answer
# if echo "$answer" | grep -iq "^y" ;then
if [ "$answer" != "${answer#[Yy]}" ] ;then # this grammar (the #[] operator) means that the variable $answer where any Y or y in 1st position will be dropped if they exist.
echo Yes
else
echo No
fi
(Thanks to Adam Katz's comment: Replaced the test above with one that is more portable and avoids one fork:)
POSIX, but single key feature
But if you don't want the user to have to hit Return, you could write:
(Edited: As #JonathanLeffler rightly suggest, saving stty's configuration could be better than simply force them to sane.)
printf 'Is this a good question (y/n)? '
old_stty_cfg=$(stty -g)
stty raw -echo ; answer=$(head -c 1) ; stty $old_stty_cfg # Careful playing with stty
if [ "$answer" != "${answer#[Yy]}" ];then
echo Yes
else
echo No
fi
Note: This was tested under sh, bash, ksh, dash and busybox!
Same, but waiting explicitly for y or n:
#/bin/sh
printf 'Is this a good question (y/n)? '
old_stty_cfg=$(stty -g)
stty raw -echo
answer=$( while ! head -c 1 | grep -i '[ny]' ;do true ;done )
stty $old_stty_cfg
if [ "$answer" != "${answer#[Yy]}" ];then
echo Yes
else
echo No
fi
Using dedicated tools
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 ...
2. Bash specific solutions
Basic in line method
read -p "Is this a good question (y/n)? " answer
case ${answer:0:1} in
y|Y )
echo Yes
;;
* )
echo No
;;
esac
I prefer to use case so I could even test for yes | ja | si | oui if needed...
in line with single key feature
Under bash, we can specify the length of intended input for for the read command:
read -n 1 -p "Is this a good question (y/n)? " answer
Under bash, read command accepts a timeout parameter, which could be useful.
read -t 3 -n 1 -p "Is this a good question (Y/n)? " answer
[ -z "$answer" ] && answer="Yes" # if 'yes' have to be default choice
Timeout with countdown:
i=6 ;while ((i-->1)) &&
! read -sn 1 -t 1 -p $'\rIs this a good question (Y/n)? '$i$'..\e[3D' answer;do
:;done ;[[ $answer == [nN] ]] && answer=No || answer=Yes ;echo "$answer "
3. Some tricks for dedicated tools
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" ) || break
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 samples? Have a look at Using whiptail for choosing USB device and USB removable storage selector: USBKeyChooser
5. Using readline's history
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.
echo "Please enter some input: "
read input_variable
echo "You entered: $input_variable"
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 :
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 ~/
Bash has select for this purpose. Here's how you would use it in a script:
select result in Yes No Cancel
do
echo $result
done
This is what it would look like to use:
$ bash examplescript.sh
1) Yes
2) No
3) Cancel
#? 1
Yes
#? 2
No
#? 3
Cancel
#?
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
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?"
...
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.
You want:
Bash builtin commands (i.e. portable)
Check TTY
Default answer
Timeout
Colored question
Snippet
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
Explanations
[[ -t 0 ]] && read ... => Call command read if TTY
read -n 1 => Wait for one character
$'\e[1;32m ... \e[0m ' => Print in green
(green is fine because readable on both white/black backgrounds)
[[ $do_xxxx =~ ^(y|Y|)$ ]] => bash regex
Timeout => Default answer is No
do_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.
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
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
It is possible to handle a locale-aware "Yes / No choice" in a POSIX shell; by using the entries of the LC_MESSAGES locale category, witch provides ready-made RegEx patterns to match an input, and strings for localized Yes No.
#!/usr/bin/env sh
# Getting LC_MESSAGES values into variables
# shellcheck disable=SC2046 # Intended IFS splitting
IFS='
' set -- $(locale LC_MESSAGES)
yesexpr="$1"
noexpr="$2"
yesstr="$3"
nostr="$4"
messages_codeset="$5" # unused here, but kept as documentation
# Display Yes / No ? prompt into locale
echo "$yesstr / $nostr ?"
# Read answer
read -r yn
# Test answer
case "$yn" in
# match only work with the character class from the expression
${yesexpr##^}) echo "answer $yesstr" ;;
${noexpr##^}) echo "answer $nostr" ;;
esac
EDIT:
As #Urhixidur mentioned in his comment:
Unfortunately, POSIX only specifies the first two (yesexpr and noexpr). On Ubuntu 16, yesstr and nostr are empty.
See: https://www.ee.ryerson.ca/~courses/ele709/susv4/xrat/V4_xbd_chap07.html#tag_21_07_03_06
LC_MESSAGES
The yesstr and nostr locale keywords and the YESSTR and NOSTR langinfo items were formerly used to match user affirmative and negative responses. In POSIX.1-2008, the yesexpr, noexpr, YESEXPR, and NOEXPR extended regular expressions have replaced them. Applications should use the general locale-based messaging facilities to issue prompting messages which include sample desired responses.
Alternatively using locales the Bash way:
#!/usr/bin/env bash
IFS=$'\n' read -r -d '' yesexpr noexpr _ < <(locale LC_MESSAGES)
printf -v yes_or_no_regex "(%s)|(%s)" "$yesexpr" "$noexpr"
printf -v prompt $"Please answer Yes (%s) or No (%s): " "$yesexpr" "$noexpr"
declare -- answer=;
until [[ "$answer" =~ $yes_or_no_regex ]]; do
read -rp "$prompt" answer
done
if [[ -n "${BASH_REMATCH[1]}" ]]; then
echo $"You answered: Yes"
else
echo $"No, was your answer."
fi
The answer is matched using locale environment's provided regexps.
To translate the remaining messages, use bash --dump-po-strings scriptname to output the po strings for localization:
#: scriptname:8
msgid "Please answer Yes (%s) or No (%s): "
msgstr ""
#: scriptname:17
msgid "You answered: Yes"
msgstr ""
#: scriptname:19
msgid "No, was your answer."
msgstr ""
To get a nice ncurses-like inputbox use the command dialog like this:
#!/bin/bash
if (dialog --title "Message" --yesno "Want to do something risky?" 6 25)
# message box will have the size 25x6 characters
then
echo "Let's do something risky"
# do something risky
else
echo "Let's stay boring"
fi
The dialog package is installed by default at least with SUSE Linux. Looks like:
In my case I needed to read from a downloaded script i.e.,
curl -Ss https://example.com/installer.sh | sh
The line read -r yn </dev/tty allowed it to read input in this case.
printf "These files will be uploaded. Is this ok? (y/N) "
read -r yn </dev/tty
if [ "$yn" = "y" ]; then
# Yes
else
# No
fi
Single keypress only
Here's a longer, but reusable and modular approach:
Returns 0=yes and 1=no
No pressing enter required - just a single character
Can press enter to accept the default choice
Can disable default choice to force a selection
Works for both zsh and bash.
Defaulting to "no" when pressing enter
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 *
Defaulting to "yes" when pressing enter
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.
No default on enter - require 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 $?
1
Here, 1 or false was returned. Note that with this lower-level function you'll need to provide your own [y/n]? prompt.
Code
# Read a single char from /dev/tty, prompting with "$*"
# 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
}
You can use the default REPLY on a read, convert to lowercase and compare to a set of variables with an expression.
The script also supports ja/si/oui
read -rp "Do you want a demo? [y/n/c] "
[[ ${REPLY,,} =~ ^(c|cancel)$ ]] && { echo "Selected Cancel"; exit 1; }
if [[ ${REPLY,,} =~ ^(y|yes|j|ja|s|si|o|oui)$ ]]; then
echo "Positive"
fi
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.
Lots of good answers to this question, but from what I can see none of them are my ideal, which would:
Be simple, just a couple lines of shell
Work with a single y/n keypress (no need to press enter)
Default to yes if you just hit enter
Work with an uppercase Y/N as well
Here's my version which does has those properties:
read -n1 -p "Continue? (Y/n) " confirm
if ! echo $confirm | grep '^[Yy]\?$'; then
exit 1
fi
You can modify that conditional to only run on "yes" (just remove the ! in the if statement) or add an else if you want to run code on both branches.
One-liner:
read -p "Continue? [Enter] → Yes, [Ctrl]+[C] → No."
This assumes that "No" and "Cancel" have the same outcome, so no reason to treat them differently.
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.
Check this
read -p "Continue? (y/n): " confirm && [[ $confirm == [yY] || $confirm == [yY][eE][sS] ]] || exit 1
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).
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"
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.
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
}
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!'
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/
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=;
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