I have a list of filenames contained in a file names "file.txt" which is like this :

```
filename1 some_block_of_text
filename2 some_block_of_text 
filename3 some_block_of_text 
filename4 some_block_of_text 
... 

```

All I want to do is to parse this file and change all the filenames with adding extension ".ext" so that my file be like this :

```
filename1.ext 
filename2.ext
filename3.ext 
filename4.ext 
... 

```

The file which contains the filenames is passed as argument so the command should be :
./my\_script.sh file.txt

I'm novice with that, should I go for something like this :

```
#!usr/bin/bash

for filename in $1 :
    rename -s /old_filename/new_file_name

```

?

Thank you in advance for your help guys