HowTo: Bash For While Loop Through File Contents Script

To loop through the contents of a file in Bash, you can use a for loop and the read command.

Here's an example of how you can use a for loop to read and process each line in a file:

#!/bin/bash

# Set the input file
input_file=input.txt

# Open the input file
while IFS= read -r line; do
  # Process the line
  echo "Line: $line"
done < "$input_file"

This script will open the file input.txt and read each line in the file one by one. The while loop reads each line and stores it in the line variable, which you can then process in the body of the loop.

You can also use a while loop and the read command to process the output of a command:

#!/bin/bash

# Set the command to run
command="ls -l"

# Run the command and process the output
while IFS= read -r line; do
  # Process the line
  echo "Line: $line"
done < <(eval "$command")

This script will run the ls -l command and read the output line by line. The <(eval "$command") syntax is known as process substitution, which allows you to use the output of a command as the input to a while loop.

Keep in mind that the read command will stop reading when it encounters the end of the file or the end of the command output. To read the entire file or command output, you need to use a loop like this.