In /usr/bin/debman line 40:
ARGS=`getopt -l help,filename:,package: -o hf:p: -n debman -- "$@"`
     ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
ARGS=$(getopt -l help,filename:,package: -o hf:p: -n debman -- "$@")


In /usr/bin/debman line 70:
if ( [ -n "$FILENAME" ] && [ -n "$PACKAGE" ] ) || \
   ^-- SC2235: Use { ..; } instead of (..) to avoid subshell overhead.


In /usr/bin/debman line 71:
   ( [ -z "$FILENAME" ] && [ -z "$PACKAGE" ] ); then
   ^-- SC2235: Use { ..; } instead of (..) to avoid subshell overhead.


In /usr/bin/debman line 83:
TEMPDIR=`mktemp -dt debman.XXXXXXXXXX`
        ^----------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
TEMPDIR=$(mktemp -dt debman.XXXXXXXXXX)


In /usr/bin/debman line 89:
    FILENAME="`find \"$TEMPDIR\" -name \*.deb -print`"
              ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    FILENAME="$(find \"$TEMPDIR\" -name \*.deb -print)"


In /usr/bin/debman line 101:
    (tar -C "$TEMPDIR" -xf - $MANDIRS 2>/dev/null || true)
                             ^------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    (tar -C "$TEMPDIR" -xf - "$MANDIRS" 2>/dev/null || true)

For more information:
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...
  https://www.shellcheck.net/wiki/SC2235 -- Use { ..; } instead of (..) to av...