Update bash-extracting_from_files.md

docs/pages/bash/bash-extracting_from_files.md

@@ -19,7 +19,15 @@ Using commands `head` and `tail` allows to do this tasks.
     tail -n 10 Fasta/enterobacteries.fasta
     ```
 
-## Counting lines (wc)
+## Counting words/lines (wc)
+
+!!! question "Count the number of characters of `enterobacteries.fasta` in the `Fasta` directory"
+
+??? example "Click to show the solution"  
+    ```bash
+    wc Fasta/enterobacteries.fasta
+    ```
+
 
 ## Sorting a tabular file (sort)