Bash script, "flash cards" for Spanish vocabulary

Question

I use this bash script to review over vocabulary with my dental Spanish class. The script works great for me. However, I am wondering what other ways the same thing could be done. How could it be more efficient? Perhaps the script could me made more readable? Maybe other areas could be made more proper or elegant? If I have done something well, then that feedback too is appreciated. I am not particularly interested in adding in checks/tests of the formatting of my vocabulary sheet or checking to make sure the file exists. The comments have my English translations of the Spanish in the script.

This script reads each line of the vocabulary file from the top to the bottom and tests whether the user knows how to say the equivalent in Spanish. It is formatted like this, English: SpanishOpt1, SpanishOpt2, SpanishOpt3. Any of the options between commas could count as correct.

This is a sample of what a vocab file looks like:

floor of the mouth: piso de la boca
cheek: mejilla, cachete
throat: garganta
change in color: cambio en color, cambio de color
taste buds: bulbos gustativos
growth: crecimiento
bruise: moretón, cardenal, magulladura, moradura, contusión

Here is the script:

#!/bin/bash

read -r -p "1 - evaluación oral
2 - radiografía
Elige uno: " opt
# Choose one.

clear

if ! [[ "$opt" =~ ^[1-2]$ ]]; then
    # That is not an option. Choose 1 or 2. 
    echo "Eso no es una opción. Elige 1 o 2."
    exit 1
fi

fname=("" "evaluación-oral-vocabulario.txt" "radiografía-vocabulario.txt")
file="/home/brock/2-Work/Dental/${fname[$opt]}"
vocab_items=$(wc -l < "$file")
line_num=1
num_right=0

until (("$line_num" > "$vocab_items")); do
    vocab_item=$(head -n"$line_num" "$file" | tail -n1)
    english=$(echo "$vocab_item" | cut -d: -f1)
    spanish=$(echo "$vocab_item" | cut -d: -f2 | sed 's/ //')
    plural_options=$(echo "$spanish" | grep ,)
    plural_vocab_item=$(echo "$spanish" | cut -d, -f1 | wc -w) 
    if [ -n "$plural_options" ] || (("$plural_vocab_item" > "1")); then
        # The "s" is to make the subject below "Las palabras" plural if needed. The "n" is for the plural verb conjugation.
        s="s"; n="n"
    else    
        s=""; n=""
    fi
    # How do you say ... in Spanish?
    read -r -p "¿Cómo se dice \"$english\" en español? " r
    answer_check=$(echo "_${spanish}_" | sed 's/, /_/g' | grep "_${r}_")
    # The "y" means "and" which is added before the last item in a list with no serial comma.
    spanish_feedback=$(echo "$spanish" | sed 's/\(.*\),/\1 y/')
    if [ -n "$answer_check" ]; then
        # You are correct. The word(s) ... mean ...
        echo -e "\tTienes razón. La$s palabra$s \"$spanish_feedback\" quiere$n decir \"$english\".\n"
        ((num_right++)) 
    else    
        # You are not correct. The word(s) ... mean ...
        echo -e "\tNo tienes razón. La$s palabra$s \"$spanish_feedback\" quiere$n decir \"$english\".\n"
        pair_wrong[$line_num]="$vocab_item\n"
    fi  
    ((line_num++))
done

# You know ... out of ... terms overall.
echo "Tú sabes $num_right de $vocab_items términos en total."
if [ -z "${pair_wrong[*]}" ]; then
    # Incredible! One hundred percent!
    echo "¡Increíble! ¡Cien por ciento!"
else
    # You have to work more on:
    echo -e "Tienes que trabajar más en:\n ${pair_wrong[*]}"
fi

Answer 1

Validating discrete choices

This is fine:

if ! [[ "$opt" =~ ^[1-2]$ ]]; then
    # That is not an option. Choose 1 or 2. 
    echo "Eso no es una opción. Elige 1 o 2."
    exit 1
fi

Another way could be using a case statement:

case "$opt" in
    [12]) ;;
    *) 
    # That is not an option. Choose 1 or 2. 
    echo "Eso no es una opción. Elige 1 o 2."
    exit 1
esac

The advantage of this is that case uses simple glob patterns, which may be easier to get right than the regex syntax in a [[ ... ]].

This alternative gets even better if we combine it with the file selection:

basedir="/home/brock/2-Work/Dental"

case "$opt" in
    1) file=$basedir/evaluación-oral-vocabulario.txt ;;
    2) file=$basedir/radiografía-vocabulario.txt ;;
    *) 
    # That is not an option. Choose 1 or 2. 
    echo "Eso no es una opción. Elige 1 o 2."
    exit 1
esac

Variables in arithmetic context

Instead of this:

until (("$line_num" > "$vocab_items")); do

You don't need to quote numeric variables, and you don't even need the dollars, this works:

until ((line_num > vocab_items)); do  

Picking a specific line from a file

Instead of this:

vocab_item=$(head -n"$line_num" "$file" | tail -n1)

This is more efficient:

vocab_item=$(sed -ne ${line_num}p)

Splitting a line into an array

@holroy already pointed out how to split the line by : to get the English and Spanish parts. You could use the same technique to split the Spanish by commas. That will also spare you the wc -w call to get the number of items, as you will be able to get it directly from the Bash array.

Emptying variables

Instead of this:

s=""; n=""

A simpler way to empty variables:

s=
n=

You could write s=; n= but it's not recommended to write multiple statements on one line.

Pattern substitution

Instead of a pipeline of echo and sed, you could use the built-in pattern substitution features of Bash. I would rewrite this part:

answer_check=$(echo "_${spanish}_" | sed 's/, /_/g' | grep "_${r}_")
spanish_feedback=$(echo "$spanish" | sed 's/\(.*\),/\1 y/')
if [ -n "$answer_check" ]; then
    # ...

Like this, using native Bash features:

spanish_feedback=${spanish//,/ y/}
if [[ _${spanish//, /_}_ == *_${r}_* ]]; then
    # ...

Answer 2

I haven't used or reviewed bash script for ever, so I'm just going to give a few comments:

• Your script reads nicely, and even though I don't know spanish, there are some comments explaining the vital parts.
• I think the script could benefit from a little more spacing, so that the various sections stood out a little more. The top half is better than the bottom half.
• The variable names are good and helpful
• However there are two code smells that I see:
  • Each time you set vocab_item you're re-reading the file. So at end of script you've read the file \$N\$ times, where \$N\$ is the number of lines
  • Each time you set english and spanish to trigger a new call to cut.

Reading the main file once

After a little searching I found this thread on SO:Looping through the content of a file in bash. The accepted answers uses the following construct:

while read p; do
  echo $p
done <peptides.txt

This would allow for reading the file just once, but you'll need to change a little of your logic related to counting the correct number of answers.

Splitting a line into an array

Another search, and another SO thread: Split string into an array in bash. This one to avoid the calls to cut.

IFS=', ' read -r -a parts <<< "$vocab_item"
english="${parts[0]}"
spanish="${parts[1]}"

Hope this helps to some extent.