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Using grep with test and without using [[ ]]

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# 15  
Old 01-24-2019
Quote:
Originally Posted by MadeInGermany
-0 feels slightly less than 0 Smilie

How about introducing a "feeling" operator (but only for almost-integers)?
# 16  
Old 01-24-2019
Quote:
Originally Posted by RudiC
How about introducing a "feeling" operator (but only for almost-integers)?
On the only 1's complement machines I've ever worked on (CDC 3600 and CDC 6500) you could have both -0 and +0. And if you used the machine language instructions to compare integer values, they tested equal (48-bit integers on the 3600 and 60-bit integers on the 6500). If you use the machine language instructions to compare their bitwise values, they tested unequal (since the sign bit was different).
These 2 Users Gave Thanks to Don Cragun For This Post:
MadeInGermany wisecracker
# 17  
Old 01-24-2019
@ Don...

I am experimenting with this in the shell ATM and does indeed have -0:
Minifloat - Wikipedia
Similarly floating point formats in general have this __anomaly__...
(Just for the record.)

@ MadeInGermany...
list ;;, yes, but it does not explain WHY, RudiC's reply just made it make sense even if there is only one command in the list.
Last edited by wisecracker; 01-24-2019 at 07:10 AM.. Reason: Error in reply.
This User Gave Thanks to wisecracker For This Post:
MadeInGermany
# 18  
Old 01-29-2019
Hi, for fun:
( bash, ksh, zsh ):
Code:
if [ -n "${XX#-}" -a "${XX#-}" = "${XX##*[^0-9]}" ]
then 
  [ "${XX#-}" -eq 0 ] && echo "$XX: null" || { [ "${XX#-}" = "${XX}" ] && echo "$XX: positif" || echo "$XX: negatif" ;}
else
  echo "$XX: ko"
fi

dash:
Code:
if [ -n "${XX#-}" -a "${XX#-}" = "${XX##*[!0-9]}" ]
then 
     [ "${XX#-}" -eq 0 ] && echo "$XX: null" || { [ "${XX#-}" =  "${XX}" ] && echo "$XX: positif" || echo "$XX: negatif" ;}
else
  echo "$XX: ko"
fi
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