do-while loop using user input in shell scritping [duplicate] - linux

Question

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Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Closed 2 years ago.
I am a beginner in bash scripting. and i look for similar questions but none gave me the results am looking for.
I want to create a shell that keep giving the user some options to choose from while the choice is not exit
Here is my code
choice=0
while [$choice!=4]
do
echo "please choose the operation you want!"
echo "1) Delete Data"
echo "2) Insert Data"
echo "3) Get Number of customers"
echo "4) Exit"
choice=$1
if [$choice=1]; then
echo "you have chosen to Delete Data"
elif [$choice=2]; then
echo "you have chosen to Insert Data"
elif [$choice=3]; then
echo "you have chosen to Get number of customers"
fi # EOF if
done
As you can see that i want my code to keep asking for the user options until the answer is not exit.
My Question is this code gives me an infinite loop.

Answer 1

Bash, ksh or zsh provides you with the select command that is exactly designed to present numbered options menu:
To get the usage of the select command, type help select in your bash terminal.
select: select NAME [in WORDS … ;] do COMMANDS; done
Select words from a list and execute commands.
The WORDS are expanded, generating a list of words. The set of expanded words is printed on the standard error, each preceded by a number. If in WORDS is not present, in "$#" is assumed. The PS3 prompt is then displayed and a line read from the standard input. If the line consists of the number corresponding to one of the displayed words, then NAME is set to that word. If the line is empty, WORDS and the prompt are redisplayed. If EOF is read, the command completes. Any other value read causes NAME to be set to null. The line read is saved in the variable REPLY. COMMANDS are executed after each selection until a break command is executed.
Exit Status:
Returns the status of the last command executed.
Here is an implementation of it with your selection menu:
#!/usr/bin/env bash
choices=('Delete Data' 'Insert Data' 'Get Number of customers' 'Exit')
PS3='Please choose the operation you want: '
select answer in "${choices[#]}"; do
case "$answer" in
"${choices[0]}")
echo 'You have chosen to Delete Data.'
;;
"${choices[1]}")
echo 'You have chosen to Insert Data.'
;;
"${choices[2]}")
echo 'You have chosen to Get number of customers.'
;;
"${choices[3]}")
echo 'You have chosen to Exit.'
break
;;
*)
printf 'Your answer %q is not a valid option!\n' "$REPLY"
;;
esac
done
unset PS3
Another implementation of the select command, using arguments rather than an array of choices:
#!/usr/bin/env ksh
PS3='Please choose the operation you want: '
set -- 'Delete Data' 'Insert Data' 'Get Number of customers' 'Exit'
select answer; do
case "$answer" in
"$1")
echo 'You have chosen to Delete Data.'
;;
"$2")
echo 'You have chosen to Insert Data.'
;;
"$3")
echo 'You have chosen to Get number of customers.'
;;
"$4")
echo 'You have chosen to Exit.'
break
;;
*)
printf 'Your answer %q is not a valid option!\n' "$REPLY"
;;
esac
done

Answer 2

If you want to use while loop with conditional 'case' syntax, try this:
while true
do
echo "1) Delete Data"
echo "2) Insert Data"
echo "3) Get Number of customers"
echo "4) Exit"
echo -ne "Enter your choice [0-4] > \c"
read choice
case "$choice" in
1) echo "you have chosen to Delete Data" ; break
;;
2) echo "you have chosen to Insert Data"; break
;;
3) echo "you have chosen to Get number of customers"; break
;;
4) exit
;;
*) clear
;;
esac
done

Answer 3

i found the error. it was statement typing issue not in the algorithm
my new code is
while [ "$(read choice)"!="4" ]
do
if [ "$choice"="1" ]; then
echo "you have chosen to Delete Data"
elif [ "$choice"="2" ]; then
echo "you have chosen to Insert Data"
elif [ "$choice"="3" ]; then
echo "you have chosen to Get number of customers"
fi # EOF if
echo "please choose the operation you want!"
echo "1) Delete Data"
echo "2) Insert Data"
echo "3) Get Number of customers"
echo "4) Exit"
done