I am trying to do the following thing the bash shell. Plz tell me how can I do this ?
ramsize=4002
ramsize=ramsize/1000
3 Answers
You can use this:
$ v=2000
$ (( v/=1000 ))
$ echo $v
2
In your case:
$ ramsize=4002
$ (( ramsize/=1000 ))
$ echo $ramsize
4
Comments
You can use expr Like this :
$ SIZE="4002"
$ DIV=$(expr "$SIZE" / "1000" )
$ MOD=$(expr "$SIZE" % "1000" )
$ echo $DIV
4
$ echo $MOD
2
back to your example:
$ ramsize=4002
$ ramsize=$( expr "$ramsize" / "1000" ) //ramsize = 4
Update the last statement according to konsolebox comment ,
the last line before modification :
$ ramsize=$("$ramsize" / "1000" )
the last line after modification :
$ ramsize=$(expr "$ramsize" / "1000" )
5 Comments
konsolebox
*
ramsize=$(("$ramsize" / "1000" )). And (( ramsize = ramsize / 1000 )) is more efficient, especially (( ramsize /= 1000 )).
bachN
*
ramsize=$(( $ramsize / 1000 )) it doesn't works when you quote vars see Arithmetic Expansion, i think C-style (()) for loops aren't POSIX , can you please explain to me why c style is more efficient?konsolebox
Probably because everything (calculations and assignments) occur in a single scope. With
ramsize=$(( $ramsize / 1000 )), $(()) would still pass the expanded value to the function that assigns the value to $ramsize.bachN
Actually i didnt see that i forgot
expr, and with your comment i realized that there is something wrong :)
chepner
expr is essentially obsolete for arithmetic, as all of its functions (other than regular-expression matching) have been incorporated into the POSIX shell via the $((...)) expression.With floats:
ramsize=4002
ramsize=$(echo "scale=4; $ramsize / 1000" | bc)
echo "$ramsize" ## Outputs 4.0020
1 Comment
prashantas
Hot to do the following ramsize=16000 freesize=3000 cachesize=8 ramsize=ramsize/1000 cachesize=freesize/1000
$ramsize: the integer division (4) or the float division (4.002)?