#! /bin/sh

LC_ALL=C
export LC_ALL
IFS='
'

pattern='(expand|head|fold|split|tail|uniq|unexpand|nice|diff)\>.*[	 ]-[a-zA-Z]*[0-9]|(sort|tail|uniq)\>.*[	 ]\+[0-9]+[a-zA-Z_]*|sort\>.*[	 ]-o'

case $1 in
--help)
  exec echo "$0: usage: $0 [OPTION]... [FILE]...
Grep for instances of possible POSIX-conformance problems in the FILEs.
Options:
  -s  Check strictly, even for things that aren't likely to be real problems.
The FILEs can be directories, in which case the greps are recursive,
though ChangeLogs, backup files, and version-control histories are bypassed.
The default FILE is '-', which stands for the standard input.";;

-s)
  pattern=$pattern'|[ef]grep\>|(\[|test\>).*[	 ]-[ao]\>'
  shift;;
esac

pattern='\<('$pattern')'

case $# in
0) exec grep -E -n "$pattern";;
*) find "${@-.}" -type f \
         ! -name '*~' ! -name 'ChangeLog*' ! -name '*,v' \
         -print \
       | sort | xargs grep -E -n "$pattern";;
esac