In /usr/bin/pic2graph line 83:
if ! tmp=`(umask 077 && mktemp -d -q "$d/pic2graph-XXXXXX") 2> /dev/null`
         ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
if ! tmp=$((umask 077 && mktemp -d -q "$d/pic2graph-XXXXXX") 2> /dev/null)


In /usr/bin/pic2graph line 102:
is_convert_recent=`convert -help | grep -e -trim`
                  ^-----------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
is_convert_recent=$(convert -help | grep -e -trim)


In /usr/bin/pic2graph line 109:
trap 'exit_status=$?; rm -rf "$tmp" && exit $exit_status' EXIT INT TERM
     ^-- SC2154: exit_status is referenced but not assigned.


In /usr/bin/pic2graph line 116:
(echo ".EQ"; echo $eqndelim; echo ".EN"; echo ".PS"; cat; echo ".PE") | \
                  ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
(echo ".EQ"; echo "$eqndelim"; echo ".EN"; echo ".PS"; cat; echo ".PE") | \


In /usr/bin/pic2graph line 118:
    && convert $convert_trim_arg $convert_opts "$tmp"/pic2graph.ps \
               ^---------------^ SC2086: Double quote to prevent globbing and word splitting.
                                 ^-----------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    && convert "$convert_trim_arg" "$convert_opts" "$tmp"/pic2graph.ps \


In /usr/bin/pic2graph line 119:
       "$tmp"/pic2graph.$format \
                        ^-----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
       "$tmp"/pic2graph."$format" \


In /usr/bin/pic2graph line 120:
    && cat "$tmp"/pic2graph.$format
                            ^-----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    && cat "$tmp"/pic2graph."$format"

For more information:
  https://www.shellcheck.net/wiki/SC2154 -- exit_status is referenced but not...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...