Updated SC2002 (markdown)

SC2002.md

@@ -3,15 +3,15 @@
 ### Problematic code:
 
 ```sh
-cat file | tr ' ' _ | grep a_
-cat file | ( while read i; do echo "${i%?}"; done )
+cat file | tr ' ' _ | nl
+cat file | while IFS= read -r i; do echo "${i%?}"; done
 ```
 
 ### Correct code:
 
 ```sh
-< file tr ' ' _ | grep a_  # **simple commands only, won't work with compounds
-( while read i; do echo "${i%?}"; done ) < file # postfix works for everything
+< file tr ' ' _ | nl  
+while IFS= read -r i; do echo "${i%?}"; done < file
 ```
 
 ### Rationale:
@@ -24,4 +24,4 @@ Many tools also accept optional filenames, e.g. `grep -q foo file` instead of `c
 
 ### Exceptions
 
-None.
+Pointing out UUOC is a long standing shell programming tradition, and removing them from a short-lived pipeline in a loop can speed it up by 2x. However, it's not necessarily a good use of time in practice, and rarely affects correctness. [[Ignore]] as you see fit.