Warning: this is an htmlized version!
The original is across this link,
and the conversion rules are here.
#!/bin/sh
# (find-angg ".fvwm/edrx-menus.fvwm")
# (find-angg ".zshrc" "myincr")
# (find-man "1 import")
# (find-angg "bin/Xscreenshot")
# (find-sh0 "Xscreenshot-rect named foo.png")
# (find-sh0 "Xscreenshot-rect")
#     (find-fline "/tmp/screenshots/foo.png")
#     (find-fline "/tmp/screenshots/")

DIR=/tmp/screenshots
FMT=/tmp/screenshots/ss%02d.png
NFILE=/tmp/screenshots/n

mkdir -p $DIR
cd       $DIR || { echo "can't cd to $DIR"; exit 1; }
if [ ! -e $NFILE ]; then 
  echo 0 > $NFILE
fi

#    N=$(cat $NFILE)
# NEWN=$[$N+1]

N     () { cat $NFILE; }
Nplus () { echo $[$(N)+1]; }
Incr  () { newN=$(Nplus); echo $newN > $NFILE; }
Img   () { printf "$FMT\n" $(N); }

doopt () {
  # case "_$1_" in
  #    _last_)  printf $FMT $N;;
  #        __)  import $(printf $FMT $NEWN)
  #             echo $NEWN > $NFILE;;
  #   _named_)  import $2;;
  #    _test_)  echo $N $NEWN;;
  #         *)  echo ERROR;;
  # esac
  case "_$1_" in
     _last_)  Img;;
         __)  import $(Img); Incr;;
    _named_)  import $2;;
     _test_)  N; Nplus;;
          *)  echo ERROR;;
  esac
}

doopt $*

return

* (eepitch-bash)
* (eepitch-kill)
* (eepitch-bash)
rm -v /tmp/screenshots/n
. ~/bin/Xscreenshot-rect test
Img

N
Nplus
Incr
N
Incr
N
echo 44 > $NFILE
N
Nplus
Nplus
echo Nplus _ $NFILE
# Nplus > $NFILE
N
cat $NFILE

Nincr
N
Nincr
N


which Nplus
set Nplus

doopt test

   N=$(cat $NFILE)
NEWN=$[$N+1]
echo $N $NEWN
echo $NEWN > $NFILE

echo $[2+3]
echo $N
N=44
echo $[$N+3]
M=$[$N+3]
echo $M
cat $NFILE


# Old code:
# mkdir -p   /tmp/screenshots
# cd         /tmp/screenshots || exit 1
# 
# if [ ! -e n ]; then 
#   echo 0 > n
# fi
# 
# N=$[$(<n)+1]
# import ss$(printf %02d $N).png
# echo $N > n