Updated SC2051 (markdown)

SC2051.md

@@ -18,7 +18,19 @@
 
 In Bash, brace expansion happens before variable expansion. This means that brace expansion will not account for variables.
 
-Use an arithmetic for loop instead.
+For integers, use an arithmetic for loop instead. For zero-padded numbers or letters, use of eval may be warranted:
+
+    from="a" to="m"
+    for c in $(eval "echo {$from..$to}"); do echo "$c"; done
+
+or more carefully (if `from`/`to` could be user input, or if the brace expansion could have spaces or globs):
+
+    from="a" to="m"
+    while IFS= read -d '' -r c
+    do
+      echo "Read $c"
+    done <  <(eval "printf '%s\0' $(printf "{%q..%q}.jpg" "$from" "$to")")
+    
 
 ### Contraindications