Bash read file line by line

I use while..do..done bash to read file line by line on linux system. The content Bash read file line by line. Bash script the essential for DevOps Roles. you can ref to Bash script tutorial.

Examples Bash read file line by line

Example 1: Using bash to read file.txt file.

[huupv@huupv devopsroles]$ cat file.txt 
Huu 30
Phan 28
foo 00

The content bash_read_file.sh file

#!/bin/bash
#To take a filename as an argument
filename="$1"
while read -r name age
do
  _NAME="$name"
  _AGE="$age"
  echo "Name read from file - ${_NAME}"
  echo "${_NAME}: Age is - ${_AGE}"
done < "$filename"

To change mode execute and run bash script

[huupv@huupv devopsroles]$ chmod +x bash_read_file.sh
[huupv@huupv devopsroles]$ ./bash_read_file.sh file.txt

The screen terminal:

Name read from file - Huu
Huu: Age is - 30
Name read from file - Phan
Phan: Age is - 28
Name read from file - foo
foo: Age is - 00

Example 2: Bash script read /etc/passwd file with fields: filed1 filed2 filed3 filed4 filed5 filed6 filed7

The content bash_read_file.sh file

#!/bin/bash
#Another thing is to take a filename as an argument.
filename="$1"
IFSOLD=$IFS
IFS=:
while read -r field1 field2 field3 field4 field5 field6 field7
do
  #display fields in /etc/passwd file
  printf 'Username: %s \t Shell: %s \t Home Dir: %s\n' "$field1" "$field7" "$field6"

done < "$filename"
IFS=$IFSOLD

The screen output terminal:

Bash read file line by line