what is wrong with my simple choice menu script?

Question

This is a simple script which should let me go to to directory of my choice, but its not working as intended.

#!/bin/bash

showMenu() {
    echo "1) ocaml"
    echo "2) python"
    echo "3) csharp"
}

while [ 1 ]
do
    showMenu
    read CHOICE
    case $CHOICE in
        "1")
            "cd ~/projects/practice/ocaml"
            ;;
        "2")
            "cd ~/projects/practice/python"
            ;;
        "3")
            "cd ~/projects/practice/csharp"
            ;;
    esac
done

I have all the necessary folders in place:

(2) [01:19 PM] ls projects/practice/
csharp/  ocaml/   python/  scripts/ web/     

Output:

(2) [01:19 PM] choice 
1) ocaml
2) python
3) csharp
1
/home/nanda/bin/choice: line 15: cd ~/projects/practice/ocaml: No such file or directory
1) ocaml
2) python
3) csharp

The script can't find the directory apparently.

I feel that I need to put the cd command, under each option, in some kind of substitution (with ${} or {}), but I am not sure how it could be done.

Also, do I need to add a break statement after each cd command?

---

I should do . choice to make it work as intended. Better yet, I put in an alias like this and it worked:

alias choice='. choice'

References:
http://stackoverflow.com/questions/255414/why-doesnt-cd-work-in-a-bash-shell-script
http://askubuntu.com/questions/84279/how-to-change-directory-using-script
http://stackoverflow.com/questions/874452/change-current-directory-from-a-script

Answer 1

You have your commands inside of quotation marks. This makes your shell treat cd ~/projects/practice/ocaml as a command name. As you don't have this command, it prints this error message. Files can contain space in their name so you could have command that has space in name. If you would like to run it, one way of doing it would be to use quotation marks as you did.

But you want your shell to run command cd and give it the path as argument. Just remote quotation marks and it should be working fine.

Whether you should or shouldn't use break statement in your script depends on what you want to do after changing directory. If you want to leave the loop then you should use it.

Note that your cd command in shell script won't change current directory after running this script. It will only affect current directory inside of the script (unless you use source instead of running it) since when you run the script, new process is created and cd only affects current directory in current and child processes, not in parent one.

Answer 2

This situation is exactly what the shell's select statement is for:

select choice in ocaml python csharp; do
    case $choice in
        ocaml|python|csharp) break ;;
    esac
done
echo cd ~/projects/practice/$choice

Slightly DRYer:

choices=(ocaml python csharp)
select choice in "${choices[@]}"; do
    [[ " ${choices[*]} " == *" $choice "* ]] && break
done
echo cd ~/projects/practice/$choice

Answer 3

You have quotes around the cd command. Remove those and you should be fine.

"cd ~/projects/practice/ocaml"

says run that command - the whole string, so it will look for such a command, including the space and the ~ and everything.

You want the command to be cd with an argument of the directory.