Read file line by line in BASH

read_file

#read a file from the command line without using the cat command 
```sh
$ while IFS= read -r line; do echo $line; done < file.txt
```

#bash script and read any file line by line
```sh
#!/bin/bash
n=1
while IFS= read -r line; do
# reading each line
echo "Line No. $n : $line"
n=$((n+1))
done < /root/file.txt
```


** take a filename as an argument and read the file line by line. **
```sh
#!/bin/bash
while IFS= read -r line; do
echo "$line is the country name"
done < $1
```


**Process Substitution allows the input or output of a command to appear as a file.**
```sh
#!/bin/bash
while IFS= read -r line
do
echo "Welcome to $line"
done < <(cat /root/file.txt )
```
**Here String allows you to pass multiple lines of input to a command**
```sh
#!/bin/bash
while IFS= read -r line
do
echo "$line"
done <<< $(cat /root/file.txt )
```