Bash: function repeats instead of running specified function

Question

I'm writing an application in Python so I'm writing an installation file for Bash. I'm having an issue where the exit() function is repeating itself rather than calling the install function from within an if statement. Here's the code...

#! /bin/bash

function install {
if [ $proceed == "y" ];
    then
        echo " "
        echo "Thank you for installing the ACS Troubleshooter!"
        echo " "
        echo "The next line is going to ask for your password to initialize a download"
        echo "sequence from the standard Ubuntu repositories"
        echo " "
            #sudo apt-get install testing
            mkdir ~/Desktop/ACSapplicationFolder
            sudo cp -r test ~/Desktop/ACSapplicationFolder
            sudo chown -R ~/Desktop/ACSapplicationFolder
        echo " "
        echo " "
        echo "The ACS Troubleshooter has been successfully installed."
        read -p "Press [ENTER] key to open the ACS Troubleshooter > "

            python gui.py &
elif [ $proceed == "n" ];
    then
        exit
fi
}

function bad_input {
echo "Please enter 'y' to continue the installation or 'n' to abort..."
    read -p "> " proceed
        if [ $proceed == "y" ];
            then
                install
        elif [ $proceed == "n" ];
            then
                exit
        else
            bad_input
        fi
    }


function exit {
        echo "The installation will exit."
        echo "   Please press [ENTER] to exit the installation or"
        echo "   press 'y' to reattempt installation."
        read -p "> " yes
            if [ "$yes" == "y" ];
                then
                    clear
                    install
            #else
                #exit 1
            fi
}



clear
echo " "
echo "                          *************************"
echo " "
echo "                       INSTALLATION: ACS TROUBLESHOOTER"
echo " "
echo "    The installer is going to install Python, the language this application"
echo "    is written in. Most computers don't have this installed by default so "
echo "    we need to do this before running the Troubleshooter. It's going to ask "
echo "    you to input your password one time to allow permission to install files "
echo "    to sensitive directories."
echo "                          *************************"
echo " "
echo " "

echo "Should we continue with the installation? (type 'y' or 'n' then press enter) "
#echo "> "
read -p "> " proceed

if [ $proceed == "y" ];
    then
        install
    elif [ $proceed == "n" ];
        then
            exit
    else
        bad_input

fi

The only function giving me trouble is exit() - the other two are working exactly as intended...

When testing the script, giving 'n' at the initial prompt runs exit(), but giving 'y' at the exit() prompt should rerun install() but it reissues the exit() prompt...getting frustrated...Can anyone answer why this is doing this?

*Note: I am just starting this so I know there are errors in install() and a few other quirks but I'm just trying to test the functions before filling in their extended instructions...

You really should have stripped down your code before posting, there is lots of stuff which has nothing to do with your problem. — user2719058
– user2719058, Commented Nov 2, 2013 at 4:04
I have since renamed exit() to abort() and it's working somewhat. However, when pressing enter to exit I get this error in terminal... ..."./install.sh: line 52: [: ==: unary operator expected"... This is referring to the start of the if statement in abort() — user2526871
– user2526871, Commented Nov 2, 2013 at 4:26

Digital Trauma · Accepted Answer · 2013-11-02 04:29:10Z

1

Some hints:

install, exit and yes are all commands or shell builtins. Giving your symbols these names is likely to cause unexpected results. I stringly recommend renaming these functions to something that is unlikely to cause such a namespace collision.
adding set -x to the start of your script (after !#/bin/bash) turns on very useful debugging
The clear command will unhelpfully clear out any hints, including debugging output from set -x - you'd do well to comment the clear commands out - at least for debugging.
watch out for your variable scoping - if function A calls function B, then function B will have access to the variables set in function A.

Having said this, your top-level scope will have $proceed set to "n" before calling your exit function. If $yes is set to "y" in the exit function, exit will call install. install then immediately checks to see if $proceed is "y", which it won't be, because it was set to "n" in the top-level scope. So install will always call exit again in this case.

I think the if statement in install is totally unnecessary as the user has already been polled, and the result checked in every instance before install is called.

answered Nov 2, 2013 at 4:29

Digital Trauma

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2 Comments

user2526871 Over a year ago

Thanks for a quality answer. You're right, the if statement in install was totally unnecessary, however, the contents of install() were originally the entire body of the script when I started - tonight I set out to break it down into functions to add extended functionality for aborting the installation and handling invalid input. I also renamed install() to app_install() - new question: pycharm keeps bugging me about saving "appinstall" to the dictionary...do you know if Bash ignores underscores where python doesn't? Again, thanks for your response.

Digital Trauma Over a year ago

@user2526871 - You're welcome! I'm afraid python is not my area, and I'd never even heard of pycharm, so I don't think I can really help out with that. If you have more questions, you should probably ask them as new questions, with the appropriate tagging.

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