LinuxQuestions.org - [SOLVED] What determines the output order from a select statement

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What determines the output order from a select statement

What determines the order a - select opt in "${!ListOfNames[@]}" Quit - statement outputs?

The script ReadTXTFile.sh

Code:

#!/bin/bash



declare -A ListOfNames



filename="$HOME/bin/DATA/TVNames.txt"

n=1

while read line; do

# reading each line

    ListOfNames[$line]=$n

n=$((n+1))

done < $filename



COLUMNS=20

PS3="Please enter your choice: "

select opt in "${!ListOfNames[@]}" Quit

do

                [[ "$REPLY" =~ [^0-9] ]] && (( REPLY = $# + 1 ))



                if (( REPLY <= ${#ListOfNames[*]} + 1 ))

                then

                        break

                else

                                echo "ERROR: Invalid choice.  Must choose one of the numbers provided."

                fi

done



if [[ "$opt" == Quit ]]

then

        echo "quitting"

else

    echo "$opt"

#

#        cat <<-OUT

#                =====================================

#                Name of TV person is: $opt

#                Prompt for filename, title, artist etc

#                =====================================

#                Now this will continue with the processing

#                part of the script.......

#                ====== Finished Okay ================

#        OUT

The above code reads this list from a file:

Code:

charlie@charlie-machine:~/bin/DATA$ ls

TVNames.txt

charlie@charlie-machine:~/bin/DATA$ cat TVNames.txt 

Carol Kirkwood - BBC Weather Girl      

Nina Warhurst - BBC News Girl    

Lorraine Kelley - ITV        

Victoria Graham - BBC Spotlight    

Kirstie Allsopp - Property Expert

Catherine Southon - Antiques Expert

Nicki Chapman - Wanted Down Under    

Holly Willoughby - ITV

IMAGES-

charlie@charlie-machine:~/bin/DATA$ ReadTXTFile.sh 

 1) Holly Willoughby - ITV

 2) Catherine Southon - Antiques Expert

 3) IMAGES-

 4) Victoria Graham - BBC Spotlight

 5) Carol Kirkwood - BBC Weather Girl

 6) Kirstie Allsopp - Property Expert

 7) Nicki Chapman - Wanted Down Under

 8) Nina Warhurst - BBC News Girl

 9) Lorraine Kelley - ITV

10) Quit

Please enter your choice:

But outputs in a different order.

It's undefined.

You're reading the list into a hash table (well, an "associative array", which is almost certainly implemented using a hash table), and then just printing out the hash table as-is. Hash tables have undefined ordering.

I agree that you should not use an associative array. There are several ways to create an array from a file.

bash 4
readarray -t ListOfNames < "$filename"

read -r -a ListOfNames <<< "$(filename)"

declare -A ListOfNames
read -r line; do
ListOfNames+=("$line")
done < "$filename"

Change your select line to
select opt in "${ListOfNames[@]}" Quit

Quote:

Originally Posted by michaelk (Post 6111090)

Changed the select line as you suggested results in this:

Code:

charlie@charlie-machine:~$ ReadTXTFile.sh 

1) 8          7) 9

2) 6          8) 7

3) 10          9) 2

4) 4          10) 3

5) 1          11) Quit

6) 5

Please enter your choice: 11

quitting

charlie@charlie-machine:~$

and the script:

Code:

#!/bin/bash



declare -A ListOfNames



filename="$HOME/bin/DATA/TVNames.txt"

n=1

while read line; do

# reading each line

    ListOfNames[$line]=$n

n=$((n+1))

done < $filename



COLUMNS=20

PS3="Please enter your choice: "

select opt in "${ListOfNames[@]}" Quit            ### <================================================

do

                [[ "$REPLY" =~ [^0-9] ]] && (( REPLY = $# + 1 ))



                if (( REPLY <= ${#ListOfNames[*]} + 1 ))

                then

                        break

                else

                                echo "ERROR: Invalid choice.  Must choose one of the numbers provided."

                fi

done



if [[ "$opt" == Quit ]]

then

        echo "quitting"

else

    echo "$opt"

Thanks anyway

Quote:

Originally Posted by dugan (Post 6111082)

Ahhh, I never thought (knew) that - I'll look into it.

Cheers

I guess I wasn't precise enough in my post. Switch to loading a standard array as suggested in my post and also change the select line.

+1 to michaelk. Replace the while loop with one mapfile command.

I don't understand why do we need associative array at all. As a minimal modification (I would do something like):

Code:

#!/bin/bash



declare -a ListOfNames  # if I remember well



filename="$HOME/bin/DATA/TVNames.txt"

while read -r line; do

# reading each line

    ListOfNames+=( "$line" )

done < $filename



COLUMNS=20

PS3="Please enter your choice: "

select opt in "${ListOfNames[@]}" Quit            ### <================================================

do

                [[ "$REPLY" =~ [^0-9] ]] && (( REPLY = $# + 1 ))



                if (( REPLY <= ${#ListOfNames[*]} + 1 ))

                then

                        break

                else

                                echo "ERROR: Invalid choice.  Must choose one of the numbers provided."

                fi

done



if [[ "$opt" == Quit ]]

then

        echo "quitting"

else

    echo "$opt"

fi

(not tested)

Quote:

Originally Posted by shruggy (Post 6111149)

+1 to michaelk. Replace the while loop with one mapfile command.

Brilliant - I didn't know the builtin command existed:

Code:

charlie@charlie-machine:~$ mapfile -t < bin/DATA/TVNames.txt 

charlie@charlie-machine:~$ printf "%s\n" "${MAPFILE[@]}"

Carol Kirkwood - BBC Weather Girl      

Nina Warhurst - BBC News Girl    

Lorraine Kelley - ITV        

Victoria Graham - BBC Spotlight    

Kirstie Allsopp - Property Expert

Catherine Southon - Antiques Expert

Nicki Chapman - Wanted Down Under    

Holly Willoughby - ITV

Susanna Reid - ITV

Neighbours - CH5 2020

Kate Garraway - ITV 2020

X

charlie@charlie-machine:~$ cat bin/DATA/TVNames.txt 

Carol Kirkwood - BBC Weather Girl      

Nina Warhurst - BBC News Girl    

Lorraine Kelley - ITV        

Victoria Graham - BBC Spotlight    

Kirstie Allsopp - Property Expert

Catherine Southon - Antiques Expert

Nicki Chapman - Wanted Down Under    

Holly Willoughby - ITV

Susanna Reid - ITV

Neighbours - CH5 2020

Kate Garraway - ITV 2020

X

thanks

Quote:

Originally Posted by pan64 (Post 6111152)

I don't understand why do we need associative array at all. As a minimal modification (I would do something like):

Code:

#!/bin/bash



declare -a ListOfNames  # if I remember well



filename="$HOME/bin/DATA/TVNames.txt"

while read -r line; do

# reading each line

    ListOfNames+=( "$line" )

done < $filename



COLUMNS=20

PS3="Please enter your choice: "

select opt in "${ListOfNames[@]}" Quit            ### <================================================

do

                [[ "$REPLY" =~ [^0-9] ]] && (( REPLY = $# + 1 ))



                if (( REPLY <= ${#ListOfNames[*]} + 1 ))

                then

                        break

                else

                                echo "ERROR: Invalid choice.  Must choose one of the numbers provided."

                fi

done



if [[ "$opt" == Quit ]]

then

        echo "quitting"

else

    echo "$opt"

fi

(not tested)

I don't need an associative array, it was the first bit of code I found that did what I wanted, almost, and I was trying to figure out what it was doing, your post worked just fine and I understand the differences now, ans updated my notes - many thanks much appreciated.

Ok, great.
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