nl: add page (fixes #1163)

pages/linux/nl.md

@@ -0,0 +1,24 @@
+# nl
+
+> A utility for numbering lines, either from a file, or from standard input.
+
+- Number lines in a file:
+
+`nl {{source_file}}`
+
+- Number lines where there is printable text only:
+
+`nl -t {{source_file}}`
+
+- Number lines that match a regular expression (Starting with a Capital 
+A is Exampled):
+
+`nl -b p^A {{source_file}}`
+
+- Can be useful as an alternative to grep {{source_file}} -n 
+{{search_term}}:
+
+`nl ./file | grep match` 
+
+Which outputs `{{line_number}} {{search_term}}`
+