Using bash script and using the case statement

Question

I'm trying to create a bash command in which you enter a number between 1 and 12 and it is using the switch command but in the bash shell the case command. I just need to make sure I have the right idea going for this or if i'm completley off

#!/bin/bash
1="January"
2="February"
3="March"
4="April"
5="May"
6="June"
7="July"
8="August"
9="September"
10="October"
11="November"
12="December"
case "1" in
print "$1"
case "2" in
print "$2" 
case "3" in
print "$3"
case "4" in
print "$4"
case "5" in
print "$5"
case "6" in
print "$6"
case "7" in
print "$7"
case "8" in
print "$8"
case "9" in
print "$9"
case "10" in
print "$10"
case "11" in
print "$11"
case "12" in 
print "$12"
echo "Please enter a number 1 through 12"
read input_variable
echo "$input_variable"

1=January isn't a valid variable assignment, either. If you wanted to set $1 through $12, you'd run: set -- January February March April May June July August September October November December. — Charles Duffy
– Charles Duffy, Commented Apr 1, 2014 at 16:18
...but, since you're using bash, the better answer is an array: declare -a months=( January February ...etc... ); read -r input_variable; echo "${months[$(( input_variable - 1))}". A case statement is overkill for this use. — Charles Duffy
– Charles Duffy, Commented Apr 1, 2014 at 16:19
@CharlesDuffy I thought the same - I have added an array-based example to my answer. — Tom Fenech
– Tom Fenech, Commented Apr 1, 2014 at 16:24
@devnull very nice, I hope you don't mind me using it in my answer. — Tom Fenech
– Tom Fenech, Commented Apr 1, 2014 at 16:28

Tom Fenech · Accepted Answer · 2014-04-01 17:11:25Z

3

I'm afraid to say you are a bit off. Here's something a bit more like it:

#!/bin/bash

echo "Please enter a number 1 through 12"
read input_variable

case $input_variable in
    1) 
        echo "January"
        ;;
    2) 
        echo "February"
        ;;
    3) 
        echo "March"
        ;;
    4) 
        echo "April"
        ;;
  # 5), 6) etc.
    *) # anything else
        echo "not recognised" 
        ;;
esac

@Charles Duffy is right, you don't actually need a case for this. You could instead use an array like this:

edit: as I write this I see an improvement from @devnull!

#!/bin/bash

echo "Please enter a number 1 through 12"
read input

months=( January February March April May June July August September October November December )

[ $input -gt 0 -a $input -le 12 ] && echo "${months[input-1]}"

or if you prefer, using a dummy entry at the start of the array (thanks @chepner)

months=( "" January February March April May June July August September October November December )

[ ! -z "${months[input]}" ] && echo "${months[input]}"

edited Apr 1, 2014 at 17:11

answered Apr 1, 2014 at 16:16

Tom Fenech

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3 Comments

user3438676 Over a year ago

Had a feeling i was pretty far off but thank you for the responce gonna give it a try

chepner Over a year ago

As a cosmetic variation, you can add a dummy element to the beginning of the array to server as Month 0; then you don't need to subtract one from the input to use it as an index.

Tom Fenech Over a year ago

@chepner thanks, I've added it as another alternative

kingstante · Accepted Answer · 2014-04-01 18:04:43Z

0

use:

read -p "Enter a number between 1 and 12: " input

as it simplifies code. Then use:

case $input in

...etc as Tom Fenech stated

But yeah case statements are more for testing against the same type of result, but performing different actions with it based on what the result turns out to be. You are echoing everything here, so yeah store the strings in an array and just output it based on the input.

answered Apr 1, 2014 at 18:04

kingstante

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