In /usr/bin/p7zip line 19:
prg7z="`which 7za 2>/dev/null`" || \
       ^---------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
prg7z="$(which 7za 2>/dev/null)" || \


In /usr/bin/p7zip line 20:
  prg7z="`which 7zr 2>/dev/null`" || \
         ^---------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  prg7z="$(which 7zr 2>/dev/null)" || \


In /usr/bin/p7zip line 84:
    tmp="`make_tmp_file`"
         ^-------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
    tmp="$(make_tmp_file)"


In /usr/bin/p7zip line 85:
    trap "rm -f -- ${tmp}" 0
                   ^----^ SC2064: Use single quotes, otherwise this expands now rather than when signalled.


In /usr/bin/p7zip line 87:
    "${prg7z}" a -si -- "${tmp}" < "${file}" >/dev/null && cat "${tmp}" || \
                                                        ^-- SC2015: Note that A && B || C is not if-then-else. C may run when A is true.


In /usr/bin/p7zip line 103:
  "${prg7z}" a $flags -- "${file}.7z" "${file}" || {  rm -f -- "${file}.7z"; exit 1; }
               ^----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
  "${prg7z}" a "$flags" -- "${file}.7z" "${file}" || {  rm -f -- "${file}.7z"; exit 1; }


In /usr/bin/p7zip line 123:
  "${prg7z}" x $flags -- "${file}" || exit 1
               ^----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
  "${prg7z}" x "$flags" -- "${file}" || exit 1


In /usr/bin/p7zip line 149:
  tmp="`make_tmp_file`"
       ^-------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
  tmp="$(make_tmp_file)"


In /usr/bin/p7zip line 150:
  trap "rm -f -- ${tmp}" 0
                 ^----^ SC2064: Use single quotes, otherwise this expands now rather than when signalled.

For more information:
  https://www.shellcheck.net/wiki/SC2064 -- Use single quotes, otherwise this...
  https://www.shellcheck.net/wiki/SC2015 -- Note that A && B || C is not if-t...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...