This script will attempt to create a copy of the input tex directory whose total size is less than the 10000 KBs (i.e., 10MBs) limit of ArXiv.

procrusteanarxiv.sh

#!/bin/bash

if [ -z "$1" ];then
  echo "USAGE:

procrusteanarxiv path/to/input/dir/containing/tex/files/

This script tested with dependencies:

gs           Ghostscript version 9.27 (9.21 is buggy)
latexmk      version 4.52c
rsync        version 2.6.9
imagemagick  version 7.0.8-12

This script will attempt to create a copy of the input tex directory whose total
size is less than the 10000 KBs (i.e., 10MBs) limit of ArXiv. It first tries:
  1. deleting all unnecessary files.
If this doesn't work, it tries to 
  2. repack all .pdf's using high-quality jpeg compression without downsampling.
If that is still not enough, it will
  3. run a binary search on the downsampling resolution to apply to all .pdf's.
"
  exit 0
fi

# gs version 9.21 has a bug that makes downsampled images ugly. Appears to be
# fixed by at least 9.27
if [[ -z "${GS}" ]]; then
  MY_GS="/Users/ajx/Downloads/ghostscript-9.27/bin/gs"
else
  MY_GS="${GS}"
fi

get_dir_size_in_b()
{
  find "$1" ! -type d -print0 | xargs -0 stat -f '%z' | awk '{sum += $1} END{print sum}'
}
get_dir_size_in_kb()
{
  #du -k -d0 "$1" | awk '{print $1;}'
  b=$(get_dir_size_in_b "$1")
  expr '(' "$b" ')' / 1000
}

get_file_size_in_kb()
{
  du -k "$1" | cut -f1
}

gs_preset()
{
  gs_file="$1"
  gstmp="/var/tmp/gstmp.pdf"
  $MY_GS -sOutputFile="$gstmp" \
    -dQUIET \
    -dNOPAUSE -dBATCH \
    -sDEVICE=pdfwrite \
    -dPDFSETTINGS=/$2 \
    -f "$gs_file"
  mv "$gstmp" "$gs_file"
}

gs_compress()
{
  res="$3"
  qfactor="$4"
  $MY_GS -sOutputFile="$2" \
    -dQUIET \
    -dNOPAUSE -dBATCH \
    -sDEVICE=pdfwrite \
    -c ".setpdfwrite << \
      /AlwaysEmbed [] \
  /AntiAliasColorImages //false \
  /AntiAliasGrayImages //false \
  /AntiAliasMonoImages //false \
  /ASCII85EncodePages //false \
  /AutoFilterColorImages //true \
  /AutoFilterGrayImages //true \
  /AutoPositionEPSFiles //true \
  /Binding /Left \
  /CalCMYKProfile (None) \
  /CalGrayProfile (None) \
  /CalRGBProfile (None)	 \
  /ColorImageDepth -1 \
  /ColorImageDict .defaultImageDict \
  /ColorImageDownsampleThreshold 1.5 \
  /ColorImageFilter /DCTEncode \
  /CompressPages //true \
  /ConvertImagesToIndexed //true \
  /DefaultRenderingIntent /Default \
  /DetectBlends //true \
  /DownsampleColorImages //true \
  /DownsampleGrayImages //true \
  /DownsampleMonoImages //true \
  /EmitDSCWarnings //false \
  /EncodeColorImages //true \
  /EncodeGrayImages //true \
  /EncodeMonoImages //true \
  /EndPage -1 \
  /GrayImageDepth -1 \
  /GrayImageDict .defaultImageDict \
  /GrayImageDownsampleThreshold 1.5 \
  /GrayImageFilter /DCTEncode \
  /ImageMemory 524288 \
  /LockDistillerParams //false \
  /MaxSubsetPct 100 \
      >> setdistillerparams" \
    -c ".setpdfwrite << \
  /MonoImageDepth -1 \
  /MonoImageDict mark \
    /K -1 \
  .dicttomark readonly \
  /MonoImageDownsampleThreshold 1.5 \
  /MonoImageFilter /CCITTFaxEncode \
  /OffOptimizations 0 \
  /OPM 1 \
  /Optimize //true \
  /ParseDSCComments //true \
  /ParseDSCCommentsForDocInfo //true \
  /PDFXTrimBoxToMediaBoxOffset [0 0 0 0] \
  /PDFXSetBleedBoxToMediaBox //true \
  /PDFXBleedBoxToTrimBoxOffset [0 0 0 0] \
  /PreserveCopyPage //true \
  /PreserveHalftoneInfo //false \
  /sRGBProfile (None) \
  /StartPage 1 \
  /SubsetFonts //true \
  /TransferFunctionInfo /Preserve \
  /UseFlateCompression //true \
  /UsePrologue //false \
  /PassThroughJPEGImages //true \
  /AutoRotatePages /None \
  /CannotEmbedFontPolicy /Error \
  /ColorACSImageDict << /QFactor $qfactor /Blend 1 /ColorTransform 1 /HSamples [2 1 1 2] /VSamples [2 1 1 2] >> \
  /ColorConversionStrategy /LeaveColorUnchanged \
  /ColorImageDownsampleType /Subsample \
  /ColorImageResolution $res \
  /CompatibilityLevel 1.7 \
  /CreateJobTicket //true \
  /DoThumbnails //true \
  /EmbedAllFonts //true \
  /GrayACSImageDict .prepressACSImageDict \
  /GrayImageDownsampleType /Bicubic \
  /GrayImageResolution 300 \
  /MonoImageDownsampleType /Subsample \
  /MonoImageResolution 1200 \
  /NeverEmbed [] \
  /PreserveEPSInfo //true \
  /PreserveOPIComments //true \
  /PreserveOverprintSettings //true \
  /UCRandBGInfo /Preserve \
      >> setdistillerparams" \
    -f "$1"
}

# https://stackoverflow.com/a/10453202/148668
# gs_compress input.pdf res jpeg
# gs_compress input.pdf 72 0.01
gs_compress_inplace()
{
  gstmp="/var/tmp/gstmp.pdf"
  gs_compress "$1" $gstmp $2 $3
  mv "$gstmp" "$1"
}

png2jpg()
{
  echo "  [debug] $1 $2"
  convert "$1" -background white -flatten -alpha off -resize 2048x2048\> -quality 90 "$2"
}

png2jpg_inplace()
{
  png2jpgtmp="/var/tmp/png2jpgtmp.jpg"
  png2jpg "$1" "$png2jpgtmp"
  mv "$png2jpgtmp" "$1"
}

png2jpg_all()
{
  find . -type f -name "*.png" -print0 | while IFS= read -r -d $'\0' file; do 
    # convert each .png file in place into a .jpg format (latex doesn't seem to
    # care about extension and this avoid needing to edit the .tex files to find
    # the new files)
    png2jpg_inplace "$file" 
  done
  find . -type f -name "*.jpg" -print0 | while IFS= read -r -d $'\0' file; do 
    png2jpg_inplace "$file" 
  done
}

# Returns the largest integer i for which `command j` succeeds (exits with a
# null exit code) where j = 10*i
function dichotomic_search_ten {
  min=$1
  max=$2
  command=$3
  while [ $min -lt $max ]; do
    # Compute the mean between min and max, rounded up to the superior unit
    current=`expr '(' "$min" + "$max" + 1 ')' / 2`
    current_times_ten=`expr 10 \*  "$current" `
    if $command $current_times_ten 1>&2
      then min=$current
      else max=`expr $current - 1`
    fi
  done
  echo $min
}



input_dir="$1"
input_base="$(basename "$input_dir")"
stripped_dir="procrustean-arxiv-stripped"
compress="procrustean-arxiv-compress"
under="$input_base-procrustean-arxiv"

##############################################################################
# Create a local copy
##############################################################################
rsync -r --exclude=.git "$input_dir" "$stripped_dir" --delete
size=$(get_dir_size_in_kb "$stripped_dir" )
echo "Original size: $size KBs"
cd "$stripped_dir"
# determine main tex file
main_tex=$(grep -l -m 1 "^[^\%]*\\\\documentclass" *.tex)
if [ -z "$main_tex" ];then
  echo "could not find main file."
  exit -1
fi

##############################################################################
# Use latexmk to build the document as a pdf and extract file list
##############################################################################

# determine basename (e.g., of .pdf or .fls)
main_base="${main_tex%.*}"
# Generating a latexmk file
echo "\$pdf_mode = 1;
\$dvi_mode = \$postscript_mode = 0;
\$pdflatex = 'pdflatex --shell-escape -synctex=1 %O %S';
@default_files = ( '$main_tex' );" > latexmkrc
if ! latexmk -silent 2>/dev/null ; then
  echo "latexmk failed"
  exit -1;
fi
# Check whether every file exists in .fls
find . -type f -print0 | while IFS= read -r -d $'\0' file; do 
  # strip "./" off the front
  file=${file:2}
  #echo "grep -qF $file $main_base.fls"
  if [ "$file" == "$main_base.fls" ]; then
    :
  elif [ "$file" == "latexmkrc" ]; then
    :
  elif [ "$file" == "$main_base.pdf" ]; then
    # just immediately remove the main pdf (it doesn't actually matter)
    rm "$file"
    continue;
  elif ! grep -iqF "$file" "$main_base.fls" ; then
    rm "$file"
    continue;
  fi
  size=$(get_file_size_in_kb "$file")
done
# clean up latexmk junk
latexmk -C -silent 2>/dev/null
# pop up
cd ../
size=$(get_dir_size_in_kb "$stripped_dir" )
echo "Removing unused files: $size KBs"

if [ "$size" -le "10000" ]; then
  rsync -r --exclude=.git "$stripped_dir/" "$under" --delete
else
  ############################################################################
  # Try simply converting to jpeg without downsampling
  ############################################################################
  rsync -r --exclude=.git "$stripped_dir/" "$compress" --delete
  cd "$compress"
  png2jpg_all
  find . -type f -name "*.pdf" -print0 | while IFS= read -r -d $'\0' file; do 
    # compress each .pdf file in place
    echo "  [debug] $file ..."
    gs_preset "$file" default
  done
  cd ..
  size=$(get_dir_size_in_kb "$compress" )
  echo "JPEG compression without downsampling: $size KBs"
  if [ "$size" -le "10000" ]; then
    rsync -r --exclude=.git "$compress/" "$under" --delete
  else
    ##########################################################################
    # Binary search over downsampling resolutions
    ##########################################################################

    # compress_and_measure 600
    compress_and_measure()
    {
      res="$1"
      echo "  [debug] res=$1"
      rsync -r --exclude=.git "$stripped_dir/" "$compress" --delete
      cd "$compress"
      png2jpg_all
      # compress and downsample each .pdf file
      find . -type f -name "*.pdf" -print0 | while IFS= read -r -d $'\0' file; do 
        echo "  [debug] $file ..."
        gs_compress_inplace "$file" $res 0.1
      done
      cd ..
      size=$(get_dir_size_in_kb "$compress" )
      echo "  [debug] size=$size"
      if [ "$size" -lt "10000" ]; then
        rsync -r --exclude=.git "$compress/" "$under" --delete
        return 0;
      else
        return 1;
      fi
    }

    ideal_res=$(dichotomic_search_ten 0 100 compress_and_measure)
    size=$(get_dir_size_in_kb "$under" )
    echo "JPEG compression with downsampling to $ideal_res dpi: $size KBs"

  fi
fi

size=$(get_dir_size_in_kb "$under" )
echo "---------------------------------------------------------------"
echo "Output \".\/$under\/\": $size KBs"

# clean up temp directories
rm -rf "$compress"
rm -rf "$stripped_dir"