In /usr/bin/dpkg-maintscript-helper line 30:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 31:
  local LASTVERSION="$2"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 32:
  local PACKAGE="$3"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 38:
  if [ "$PACKAGE" = "--" -o -z "$PACKAGE" ]; then
                         ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 42:
  while [ "$1" != "--" -a $# -gt 0 ]; do
                       ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 64:
    if [ "$1" = "install" -o "$1" = "upgrade" ] && [ -n "$2" ] &&
                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 81:
    if [ "$1" = "abort-install" -o "$1" = "abort-upgrade" ] &&
                                ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 94:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 95:
  local PACKAGE="$2"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 100:
  local md5sum old_md5sum
  ^---------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 112:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 126:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 127:
  local PACKAGE="$2"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 145:
  local OLDCONFFILE="$1"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 146:
  local NEWCONFFILE="$2"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 147:
  local LASTVERSION="$3"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 148:
  local PACKAGE="$4"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 154:
  if [ "$PACKAGE" = "--" -o -z "$PACKAGE" ]; then
                         ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 158:
  while [ "$1" != "--" -a $# -gt 0 ]; do
                       ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 182:
    if [ "$1" = "install" -o "$1" = "upgrade" ] && [ -n "$2" ] &&
                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 194:
    if [ "$1" = "abort-install" -o "$1" = "abort-upgrade" ] &&
                                ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 207:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 208:
  local PACKAGE="$2"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 214:
  local md5sum old_md5sum
  ^---------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 224:
  local OLDCONFFILE="$1"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 225:
  local NEWCONFFILE="$2"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 226:
  local PACKAGE="$3"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 241:
  local CONFFILE="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 242:
  local PACKAGE="$2"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 256:
  local SYMLINK="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 257:
  local SYMLINK_TARGET="$2"
  ^------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 258:
  local LASTVERSION="$3"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 259:
  local PACKAGE="$4"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 265:
  if [ "$PACKAGE" = "--" -o -z "$PACKAGE" ]; then
                         ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 270:
  while [ "$1" != "--" -a $# -gt 0 ]; do
                       ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 297:
    if [ "$1" = "install" -o "$1" = "upgrade" ] &&
                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 320:
    if [ "$1" = "abort-install" -o "$1" = "abort-upgrade" ] &&
                                ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 340:
  local PATHNAME="${1%/}"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 341:
  local SYMLINK_TARGET="$2"
  ^------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 342:
  local LASTVERSION="$3"
  ^---------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 343:
  local PACKAGE="$4"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 349:
  if [ "$PACKAGE" = "--" -o -z "$PACKAGE" ]; then
                         ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 354:
  while [ "$1" != "--" -a $# -gt 0 ]; do
                       ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 379:
    if [ "$1" = "install" -o "$1" = "upgrade" ] &&
                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 405:
    if [ "$1" = "abort-install" -o "$1" = "abort-upgrade" ] &&
                                ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 408:
       [ \( ! -h "$DPKG_ROOT$PATHNAME" -a \
                                       ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 409:
            -d "$DPKG_ROOT$PATHNAME" -a \
                                     ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 410:
            -f "$DPKG_ROOT$PATHNAME/.dpkg-staging-dir" \) -o \
                                                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 411:
         \( -h "$DPKG_ROOT$PATHNAME" -a \
                                     ^-- SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 412:
            \( "$(readlink "$DPKG_ROOT$PATHNAME")" = "$SYMLINK_TARGET" -o \
                                                                       ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.


In /usr/bin/dpkg-maintscript-helper line 426:
  local PACKAGE="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 427:
  local PATHNAME="$2"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 429:
  local LINE
  ^--------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 472:
  local PATHNAME="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 473:
  local SYMLINK_TARGET="$2"
  ^------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 478:
  local ABS_SYMLINK_TARGET
  ^----------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 501:
  local PATHNAME="$1"
  ^------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 518:
  local VERSION="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 530:
  local PACKAGE="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 531:
  local FILE="$2"
  ^--------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 543:
  local PACKAGE="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 544:
  local FILE="${2##$DPKG_ROOT}"
  ^--------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 558:
  local SYMLINK="$1"
  ^-----------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 559:
  local SYMLINK_TARGET="$2"
  ^------------------^ SC2039: In POSIX sh, 'local' is undefined.


In /usr/bin/dpkg-maintscript-helper line 605:
. "$PKGDATADIR/sh/dpkg-error.sh"
  ^----------------------------^ SC1090: Can't follow non-constant source. Use a directive to specify location.

For more information:
  https://www.shellcheck.net/wiki/SC1090 -- Can't follow non-constant source....
  https://www.shellcheck.net/wiki/SC2039 -- In POSIX sh, 'local' is undefined.
  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...