Profiling AWK vs GREP in sorting file contents in custom order (AWK is 2 times faster)

awk_vs_grep.sh

#! /usr/bin/env sh

###
### awk_vs_grep.sh - Profiles 2 methods used to sort file contents using custom pattern
### make sure to have file "awk_vs_grep.txt" with some content
### for more details refer to this Question: http://unix.stackexchange.com/questions/75498/sort-using-custom-pattern/
###
### Usage: `./awk_vs_grep.sh` - will execute commands 10 times and only print profile results
### Usage: `./awk_vs_grep.sh 1000` - will execute commands 1000 times and only print profile results
### Usage: `./awk_vs_grep.sh 1000 /dev/tty` - will execute commands 1000 times and print commands output + results

# how many times to run profiled commands - default 10
TIMES=${1:-10}
# define OUT for profiled commands - default null device
OUT=${2:-/dev/null}


# Define Helpers
function currtime() {
  echo $(date +%s%N)
}
function diff_in_seconds() {
  start_time=$2
  end_time=$1
  echo "scale=3;($end_time - $start_time)/(1*10^09)" | bc
}

# Profile AWK method
AWK_START_TIME=$(currtime)
  for ((n=0; n<$TIMES; n++)); do
    sort awk_vs_grep.txt | awk '$0 ~ /^b/  || $0 ~ /^d/ {print} $0 !~ /^b/ && $0 !~ /^d/ { a[f++] = $0 } END { for (word = 0; word < f; word++) { print a[word] } }' > $OUT
  done
AWK_TIME=$(diff_in_seconds $(currtime) $AWK_START_TIME)

# Profile GREP method
GREP_START_TIME=$(currtime)
  for ((n=0; n<$TIMES; n++)); do
    grep '^b' awk_vs_grep.txt > $OUT
    grep '^d' awk_vs_grep.txt > $OUT
    grep -v '^b' awk_vs_grep.txt | grep -v '^d' | sort > $OUT
  done
GREP_TIME=$(diff_in_seconds $(currtime) $GREP_START_TIME)

# Print Results
echo "Executed commands $TIMES times"
echo "AWK total time: $AWK_TIME seconds"
echo "GREP total time: $GREP_TIME seconds"

awk_vs_grep.txt

b
d
c
a