Bash: Take argument 1 of each line in a file and put it into an array

Question

I have a file that contains many lines. Each line consists of first, a 1 word string, and second, a number (argument 1 and argument 2 are separated by a space). I need to create a script that goes through each line, and assigns argument 1 to an array, and argument 2 to another array. I then need to print both arrays in the same order they were in (in the file) using a loop. Then I must bubble sort the strings (arg1) in alphabetical order, but the numbers (arg2) must follow the string in the same order they were in when they were in the file. I then need to print both arguments (now alphabetical, but with original numbers along side) in their new sorted order.

Here is what I assume it should look like, but I can't get working:

for line in ${filename[*]}; do
    for (( i=0; i<=${#filename[*]}; i++ )); do
        array=( $(array + arg1) )
    done
done

The "array + arg1" is just what I can't figure out. I just can't seem to find out how to get the 1st argument of each line and put it into an array. You'd think it would be simple.

Answer 1

There are many ways to do what you need, here is one as an example:

My file list, with 1 word string and a number for each line:

cat mylist.txt
word_b 20
word_h 80
word_c 30
word_e 50
word_d 40
word_f 60
word_g 70
word_a 10

So, you can do something like this:

#!/bin/bash

# Declare arrays
words_array=()
numbers_array=()

# Read line by line from SORTED file list
filename="mylist.txt"
IFS=$'\n'
for line in `cat $filename | sort`; do
  # Assign the word in the first position and the number in the second to variables
  word=$(echo $line|awk '{print $1}')
  number=$(echo $line|awk '{print $2}')
  # Append values to each array
  words_array+=("$word")
  numbers_array+=("$number")
done

# Then use loop and share iterator between arrays
for (( i=0; i<=${#words_array[@]}; i++ )); do
  echo  "${words_array[$i]} ${numbers_array[$i]}"
done

Output:

./myscript.sh
word_a 10
word_b 20
word_c 30
word_d 40
word_e 50
word_f 60
word_g 70
word_h 80