Bash script with user prompt

Question

I am very new to bash scripting. I am trying to create a script which creates a local txt file that is treated as a database. The commands the user can use is: quit, add, delete, printdb. How would I create a user prompt? If the user inputs quit how would I set up the quit function to quit the script and how would I pass the user input into the function?

I have done:

#!/bin/bash
func () {
echo -n "% "
read answer
}
if [ $answer != "quit" ] && [ $answer != "setdb" ] && [ $answer != "add" ] && [ $answer != "delete" ] && [
$answer != "printdb" ]
then
 echo "Unrecognised command"
 func
else
 echo -n "%"
fi



#quit () {}

#setdb (){}

#add () {}

#delete () {}

#printdb () []

But it does not recognize if the commands are not valid.

You really should read a tutorial. If you have already worked on a script, post it in your question. Regards — Éric, May 17 '20 at 20:55
You should use a `switch` instead of `if`: https://stackoverflow.com/questions/5562253/switch-case-with-fallthrough . Regards — Éric, May 17 '20 at 21:25
and in shell scripting, `switch` statements are expressed as `case ${answer} in quit ) exit 0 ;; setdb ) set DB=$1 ;; * ) echo Unknown option provided $* ;; esac`. Good luck. — shellter, May 17 '20 at 21:53

score 0 · Answer 1 · edited Mar 29 '23 at 04:54

This shows how you can use read and case to read input.

#!/bin/bash
while true; do
      echo -n "Enter command."
      read -r m
      case $m in
      quit) exit 0 ;; # exit without error
      add) echo "New line" >> printdb.txt ;; # add new line
      delete) sed -i '$d' printdb.txt ;; # delete last line
      printdb) cat printdb.txt ;; # show file
      *) echo "ERROR:Unknown command".; exit 1 ;; # handle invalid command
      esac
done

References:

Bash script with user prompt

1 Answers1