prefix: compatibility tweaks

Author: Smattr

prefix

@@ -3,14 +3,14 @@
 # Prefix the output of a command with some given text.
 
 if [ $# -lt 2 ]; then
-    echo "Usage: $0 text command" >&2
-    exit 1
+  printf "Usage: %s text command\n" "$0" >&2
+  exit 1
 fi
 
 PREFIX=$1
 shift
 
 $@ | while read line; do
-    echo "${PREFIX}${line}"
+  printf "%s%s\n" "${PREFIX}" "${line}"
 done
 exit ${PIPESTATUS[0]}