How to use shell to read files row by row

When learning Linux shell scripts, one of the most common errors is to useFor(For line in $ (cat file.txt) do ...) Read files row by row. The following example shows the result.

File file.txt content:

Cat file.txt

This is the Row No 1;

This is the Row No 2;

This is the Row No 3.

 

UseForLoop example:

For line in $ (cat file.txt); Do echo $ line; done

This

Is

The

Row

No

1;

This

Is

The

Row

No

2;

[…]

Obviously, this is not what we want. The solution is to use a while loop with internal reads.

WhileLoop is the most appropriate and simple way to read files row by row:

While read line; do echo $ line; done

This is the Row No 1;

This is the Row No 2;

This is the Row No 3.