如何在Linux中脱颖而出

Question

I want to take the input from the user, which could be any of the given options, I tried using select , but it just goes in loop, doesn't come out, is there a way i can make it to come out and proceed after the user has entered right option, here is the sample code:

select envir in "prod" "uat" "dev"; do
    echo $envir
done

//continue with the script
echo "out of select"

Once user selects any of the available options, it should come out and continue with the scripts, if the user has entered anything else, it should keep on prompting.

Answer 1

select envir in "prod" "uat" "dev"; do
    echo $envir
    if [ $envir == "prod" ] || [ $envir == "uat" ] || [ $envir == "dev" ]
    then
        break
    fi
done

//continue with the script
echo "out of select"

Answer 2

From the bash(1) man page:

... The list is executed after each selection until a break command is executed. The exit status of select is the exit status of the last command executed in list, or zero if no commands were exe- cuted. ...

In other words, execute a "break" statement when $envir is nonempty.

Answer 3

I would write the above script this way:

#!/bin/bash
declare -a opts=("prod" "uat" "dev")

echo "control-D to exit"
select envir in "${opts[@]}"; do
    echo "envir=$envir"
    found=0
    for elem in "${opts[@]}"; do
       if [ "$elem" = "$envir" ]; then
          found=1
          break
       fi
    done
    if [ "$found" -eq 1 ]; then
       break
    fi
done

echo "out of select"

That way your keywords are handled at one place. Every time you add a new word in the list of "prod" "uat" "dev", you don't need to change at 2 places.

You can also read the list of words from an external file and assign that to bash array variable opts here.

Answer 4

Thanks Brian. With your input, this is what I was able to do:

select envir in "prod" "uat" "dev"; do
    echo $envir
    if [ "$envir" != "" ]
    then
        break
    fi
done

//continue with the script
echo "out of select"