xereeto's terminal image viewer

#!/bin/bash
# this will be important later:
imgvwr="$(locate w3m-img)"
if [ -z "$1" ]; then
    echo "must specify a filename."
    exit 1
elif [ -z "$(which w3m)" ]; then
    echo "Error: w3m must be installed."
    exit 1
elif  [ "$(expr index '$imgvwr' '/usr/share/doc/w3m-img')" == "0" ]; then
    # remember the imgvwr from before?
    echo "Error: w3m-img must be installed."
    exit 1
fi
S1="$1"
# if a relative path has been given,
# add the currrent directory to it
if [ ! "${1:0:1}" == "/" ]; then
    S1="$(pwd)/$1"
fi
# for aesthetics only, so we
# can display the filename
S2="$(basename $S1)"
# creates the temporary HTML document so we can view the image
echo "<html><head><title>$S2</title></head><body>&nbsp;<img src='$S1' alt='$S2'><br>&nbsp;</body></html>" > /tmp/xerimgvwr.$$.html
w3m /tmp/xerimgvwr.html
# tidy up time
rm /tmp/xerimgvwr.html