/usr/bin/pnmindex is in netpbm 2:10.0-15.2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 | #!/bin/bash
#
# pnmindex - build a visual index of a bunch of anymaps
#
# Copyright (C) 1991 by Jef Poskanzer.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted, provided
# that the above copyright notice appear in all copies and that both that
# copyright notice and this permission notice appear in supporting
# documentation.  This software is provided "as is" without express or
# implied warranty.
size=100        # make the images about this big
across=6        # show this many images per row
colors=256      # quantize results to this many colors
back="-white"   # default background color
doquant=true    # quantize or not
title=""        # default title (none)
usage ()
{
  echo "usage: $0 [-size N] [-across N] [-colors N] [-black] pnmfile ..."
  exit 1
}
while :; do
    case "$1" in
    -s*)
        if [ $# -lt 2 ]; then usage; fi
        size="$2"
        shift
        shift
    ;;
    -a*)
        if [ $# -lt 2 ]; then usage; fi
        across="$2"
        shift
        shift
    ;;
    -t*)
        if [ $# -lt 2 ]; then usage; fi
        title="$2"
        shift
        shift
    ;;
    -c*)
        if [ $# -lt 2 ]; then usage; fi
        colors="$2"
        shift
        shift
    ;;
    -b*)
        back="-black"
        shift
    ;;
    -w*)
        back="-white"
        shift
    ;;
    -noq*)
        doquant=false
        shift
    ;;
    -q*)
        doquant=true
        shift
    ;;
    -*)
        usage
    ;;
    *)
        break
    ;;
    esac
done
if [ $# -eq 0 ]; then
    usage
fi
tmpdir=$(mktemp -d -t pi.XXXXXXXX) || exit 1 #219019
tmpfile=$tmpdir/pi.tmp
maxformat=PBM
rowfiles=()
imagefiles=()
row=1
col=1
if [ "$title"x != ""x ] ; then
#    rowfile=`tempfile -p pirow -m 600`
    rowfile=$tmpdir/pi.${row}
    pbmtext "$title" > $rowfile
    rowfiles=(${rowfiles[*]} $rowfile )
    row=$(($row + 1))
fi
for i in "$@"; do
    cp "$i" $tmpfile
    description=(`pnmfile $tmpfile`)
    format=${description[1]}
    width=${description[3]}
    height=${description[5]}
    if [ $? -ne 0 ]; then
        echo pnmfile returned an error
        exit $?
    fi
    if [ $width -gt $size ] || \
       [ $height -gt $size ]; then
        case $format in
        PBM) 
            pnmscale -quiet -xysize $size $size $i | pgmtopbm > $tmpfile
        ;;
        PGM)
            pnmscale -quiet -xysize $size $size $i > $tmpfile
            if [ $maxformat = PBM ]; then
                maxformat=PGM
            fi
        ;;
        *) 
            if [ "$doquant" = "true" ] ; then
                pnmscale -quiet -xysize $size $size $i | \
                ppmquant -quiet $colors > $tmpfile
            else
                pnmscale -quiet -xysize $size $size $i > $tmpfile
            fi
            maxformat=PPM
        ;;
        esac
    fi
    imagefile=$tmpdir/pi.${row}.${col}
    rm -f $imagefile
    if [ "$back" = "-white" ]; then
        pbmtext "$i" | pnmcat $back -tb $tmpfile - > $imagefile
    else
        pbmtext "$i" | pnminvert | pnmcat $back -tb $tmpfile - > $imagefile
    fi
    rm -f $tmpfile
    imagefiles=( ${imagefiles[*]} $imagefile )
    if [ $col -ge $across ]; then
        rowfile=$tmpdir/pi.${row}
        rm -f $rowfile
        if [ $maxformat != PPM -o "$doquant" = "false" ]; then
            pnmcat $back -lr -jbottom ${imagefiles[*]} > $rowfile
        else
            pnmcat $back -lr -jbottom ${imagefiles[*]} | \
            ppmquant -quiet $colors > $rowfile
        fi
        rm -f ${imagefiles[*]}
        unset imagefiles
        imagefiles=()
        rowfiles=( ${rowfiles[*]} $rowfile )
        col=1
        row=$(($row + 1))
    else
        col=$(($col + 1))
    fi
done
# All the full rows have been put in row files.  
# Now put the final partial row in its row file.
if [ ${#imagefiles[*]} -gt 0 ]; then
    rowfile=$tmpdir/pi.${row}
    rm -f $rowfile
    if [ $maxformat != PPM -o "$doquant" = "false" ]; then
        pnmcat $back -lr -jbottom ${imagefiles[*]} > $rowfile
    else
        pnmcat $back -lr -jbottom ${imagefiles[*]} | \
        ppmquant -quiet $colors > $rowfile
    fi
    rm -f ${imagefiles[*]}
    rowfiles=( ${rowfiles[*]} $rowfile )
fi
if [ ${#rowfiles[*]} -eq 1 ]; then
    cat $rowfiles
else
    if [ $maxformat != PPM -o "$doquant" = "false" ]; then
        pnmcat $back -tb ${rowfiles[*]}
    else
        pnmcat $back -tb ${rowfiles[*]} | ppmquant -quiet $colors
    fi
fi
rm -f ${rowfiles[*]}
if [ -d "$tmpdir" ]; then
    rm -rf "$tmpdir";
fi
exit 0
 |