Looping through the content of a file in Bash

Question

How do I iterate through each line of a text file with Bash?

With this script:

echo \"Start!\"
for p in (peptides.txt)
do
    echo \"${p}\"
done
         


        

Answer 1

Option 1a: While loop: Single line at a time: Input redirection

#!/bin/bash
filename='peptides.txt'
echo Start
while read p; do 
    echo $p
done < $filename

Option 1b: While loop: Single line at a time:
Open the file, read from a file descriptor (in this case file descriptor #4).

#!/bin/bash
filename='peptides.txt'
exec 4<$filename
echo Start
while read -u4 p ; do
    echo $p
done