Command line option handling strategies

README.md

= Argument handling strategies

# generate 1k,10k worth of arg data
ruby -e '200.times  {|i| puts("%.5d" % i) }' > 1k.txt
ruby -e '2000.times {|i| puts("%.5d" % i) }' > 10k.txt

# check size, bytes should be 1k
cat 1k.txt | tr -d "\n" | wc

# baseline
time tr "\n" " " < 1k.txt                             # 0.005
ps -l | grep -- $0 | grep -v grep | awk '{print $9}'  # 0.015 ~

# strategies
time ./echo_args    $(tr "\n" " " < 1k.txt) # 0.028, 828
time ./shift_args   $(tr "\n" " " < 1k.txt) # 0.030, 804
time ./set_args     $(tr "\n" " " < 1k.txt) # 0.120, 828
time ./append_args  $(tr "\n" " " < 1k.txt) # 0.274, 848
time ./parse_args   $(tr "\n" " " < 1k.txt) # 0.046, 864
time ./reorder_args $(tr "\n" " " < 1k.txt) # 0.066, 864

append_args

#!/bin/bash

set -- "$@" --
while [[ $1 != '--' ]]
do
  set -- "$@" "$1"
  shift
done

echo $@

ps -l | grep -- $0 | grep -v grep | awk '{print $9}'

echo_args

#!/bin/bash

echo "$@"

ps -l | grep -- $0 | grep -v grep | awk '{print $9}'

parse_args

#!/bin/bash

optparse () {
  n=1
  while [[ $n -lt $# ]]
  do
    n=$(($n + 1))
    printf " \${%d}" $n
  done
}

eval set -- $(optparse "$@")
echo $@

ps -l | grep -- $0 | grep -v grep | awk '{print $9}'

reorder_args

#!/bin/bash

eval set -- $(
vals=""
while [ $OPTIND -le $# ]
do
  if getopts "achmrst:v" ts_option
  then
    if [ $OPTARG ]
    then printf " -%s \${%d}" $ts_option $(($OPTIND - 1))
    else printf " -%s" $ts_option
    fi
  else
    vals="$vals \${$OPTIND}" 
    OPTIND=$(($OPTIND + 1))
  fi
done
printf "%s" "$vals"
)

echo $@
ps -l | grep -- $0 | grep -v grep | awk '{print $9}'

set_args

#!/bin/bash

while [[ $# -gt 0 ]]
do
  set $@
  shift 1
done

echo $@

ps -l | grep -- $0 | grep -v grep | awk '{print $9}'

shift_args

#!/bin/bash

while [[ $# -gt 0 ]]
do shift 1
done

echo $@

ps -l | grep -- $0 | grep -v grep | awk '{print $9}'