Hexadecimal To Decimal in Shell Script

Question

Can someone help me to convert a hexadecimal number to decimal number in a shell script   E g   I want to convert the hexadecimal number bfca3000 to decimal using a shell script  I basically want the difference of two hexadecimal numbers   My code is   var3  echo  ibase 16   var1    bc  var4  echo  ibase 16   var2    bc  var5     var4- var3                    Line 48    When executing  I get this error   Line 48  -  syntax error  operand expected  error token is  -

User · Answer

Dealing with a very lightweight embedded version of busybox on Linux means many of the traditional commands are not available (bc, printf, dc, perl, python)

echo $((0x2f))
47

hexNum=2f
echo $((0x${hexNum}))
47

Credit to Peter Leung for this solution.

User · Answer

I have this handy script on my  PATH to filter 0x1337-like  1337  or  quot 0x1337 quot  lines of input into decimal strings  expanded for clarity      usr bin env bash  while read data  do   withoutQuotes  echo   data    sed s   quot   g    without0x  echo   withoutQuotes    sed s 0x  g    clean   without0x    echo    16   clean    done

User · Answer

To convert from hex to decimal  there are many ways to do it in the shell or with an external program   With bash     echo    16 FF   255   with bc     echo  ibase 16  FF    bc 255   with perl     perl -le  print hex  FF     255   with printf      printf   d n  0xFF 255   with python     python -c  print int  FF   16    255   with ruby     ruby -e  p  FF  to i 16   255   with node js     nodejs  lt  lt  lt   console log parseInt  FF   16    255   with rhino     rhino lt  lt EOF print parseInt  FF   16   EOF     255   with groovy     groovy -e  println Integer parseInt  FF  16   255

User · Answer

Shortest way yet    echo   0x3F  63

User · Answer

In dash and other shells  you can use  printf   d n   your hexadecimal number    to convert a hexadecimal number to decimal  This is not bash  or ksh  specific

User · Answer

One more way to do it using the shell  bash or ksh  doesn t work with dash    echo    16 FF   255

User · Answer

Various tools are available to you from within a shell   Sputnick has given you an excellent overview of your options  based on your initial question   He definitely deserves votes for the time he spent giving you multiple correct answers   One more that s not on his list    ghoti pc     dc -e  16i BFCA3000 p  3217698816   But if all you want to do is subtract  why bother changing the input to base 10    ghoti pc     dc -e  16i BFCA3000 17FF - p 10o p  3217692673 BFCA1801  ghoti pc        The dc command is  desk calc    It will also take input from stdin  like bc  but instead of using  order of operations   it uses stacking   reverse Polish   notation   You give it inputs which it adds to a stack  then give it operators that pop items off the stack  and push back on the results   In the commands above we ve got the following    16i -- tells dc to accept input in base 16  hexadecimal   Doesn t change output base  BFCA3000 -- your initial number 17FF -- a random hex number I picked to subtract from your initial number - -- take the two numbers we ve pushed  and subtract the later one from the earlier one  then push the result back onto the stack p -- print the last item on the stack   This doesn t change the stack  so    10o -- tells dc to print its output in base  10   but remember that our input numbering scheme is currently hexadecimal  so  10  means  16   p -- print the last item on the stack again     this time in hex    You can construct fabulously complex math solutions with dc   It s a good thing to have in your toolbox for shell scripts

User · Answer

The error as reported appears when the variables are null  or empty      unset var3 var4  var5     var4- var3   bash  -  syntax error  operand expected  error token is  -     That could happen because the value given to bc was incorrect  That might well be that bc needs UPPERcase values  It needs BFCA3000  not bfca3000  That is easily fixed in bash  just use the    expansion   var3 bfca3000  var3  echo  ibase 16    var1       bc    That will change the script to this      bin bash  var1  bfca3000  var2  efca3250   var3    echo  ibase 16    var1       bc   var4    echo  ibase 16    var2       bc    var5      var4- var3     echo  Diference  var5    But there is no need to use bc  1   as bash could perform the translation and substraction directly      bin bash  var1  bfca3000  var2  efca3250   var5      16  var2 - 16  var1      echo  Diference  var5     1 Note  I am assuming the values could be represented in 64 bit math  as the difference was calculated in bash in your original script  Bash is limited to integers less than   2  63 -1  if compiled in 64 bits  That will be the only difference with bc which does not have such limit

[bash] Hexadecimal To Decimal in Shell Script

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