s6-portable-utils
Software
www.skarnet.org
 The s6-nice program 
 s6-nice executes into a program with an altered nice value.
 Interface 
     s6-nice [ -I | -i ] [ -n value ] [ prog... ]
 s6-nice acts as the generic
nice utility.
 Extra options 
 -  -I : loose. If the nice value cannot be set to value,
print a warning message and exec into prog... anyway. This is the default. 
-  -i : strict. If the nice value cannot be set to value,
exit 111 with an error message.
 Posixness 
 s6-nice is suitable as a Single Unix
nice
program.