ajout exo pour redirection avec &&

docs/pages/bash/bash-extracting_from_files.md

@@ -186,6 +186,13 @@ You can redirect a result and store it in a file thanks to the `>` redirection:
     grep ";2005;" nat2021.csv > selected_names.txt
     ```
 
+!!! question "Erase the file `selected_names.txt`and reproduce the pratice by chaining commands with `&&`"
+
+??? example "Click to show the solution"  
+    ```bash
+    rm -rf selected_names.txt && grep ";2005;" nat2021.csv > selected_names.txt && grep ";2006;" nat2021.csv >> selected_names.txt && wc -l selected_names.txt && grep ";2007;" nat2021.csv >> selected_names.txt && wc -l selected_names.txt
+    ```
+
 !!! question "Add all names from 2006 and 2007 into this file. Check the number of lines after each action"
 
 ??? example "Click to show the solution"  
@@ -197,7 +204,6 @@ You can redirect a result and store it in a file thanks to the `>` redirection:
     wc -l selected_names.txt
     ```
 
-
 ## Replacing patterns (sed)