"bc" Command

Learn all about bc command

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bc is a language that supports arbitrary precision numbers with interactive execution of statements. There are some similarities in the syntax to the C programming language. A standard math library is available by command line option. All code is executed as it is read. More information can be found in its manual:

root:~# man bc

Example-1

bc can be run in interactive mode.

root:~# bc
bc 1.06.95
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.

1+1
2
x=1
y=4
x+y
5
last+10
15
quit

root:~# bc -q
1+3
4
quit

Here,
-q option is used to supress welcome message.
last keyword will use last value.
quit keyword will be used to exit from interactive mode.

Example-2

Basic calculations can be done using following.
Note: There shouldnt be any space on either side of sign (-,+,*,/)

root@:~# bc <<< 5-4
1
root@:~# bc <<< 5-4+2
3
root@:~# bc <<< 5-4+2+\(1+4\)*3
18

Default base will be 10 so to convert base user can do following.

root@:~# echo "obase=16; ibase=10; 60" | bc
3C
root@:~# echo 'obase=2;128' | bc
10000000

Where ibase denotes Input Base and obase denotes Output Base.

root@:~# echo "scale=6;  62/7.02" | bc
8.831908
root@:~# echo "scale=2;  62/7.02" | bc
8.83
root@:~# echo "62/7.02" | bc
8

Here, scale keyword define how many digit after the point. By Default the scale is 0, that means its integer.

Example-3

The following is code that uses the extended features of bc to implement a simple program for calculating checkbook balances. This program is best kept in a file so that it can be used many times without having to retype it at every use.

root@:~# cat calc.txt
scale=2
print "\nCheck book program\n!"
print "  Remember, deposits are negative transactions.\n"
print "  Exit by a 0 transaction.\n\n"

print "Initial balance? "; bal = read()
bal /= 1
print "\n"
while (1) {
  "current balance = "; bal
  "transaction? "; trans = read()
  if (trans == 0) break;
  bal -= trans
  bal /= 1
}
quit

root@:~# bc -q calc.txt

Check book program
!  Remember, deposits are negative transactions.
  Exit by a 0 transaction.

Initial balance? 100

current balance = 100.00
transaction? 20
current balance = 80.00
transaction? 50
current balance = 30.00
transaction? -10
current balance = 40.00
transaction? 20
current balance = 20.00
transaction? 40
current balance = -20.00
transaction? 20
current balance = -40.00
transaction? 0

Example-4

To check current limits of bc, go to interactive mode and then type limits.

root@:~# bc -q
limits
BC_BASE_MAX     = 2147483647
BC_DIM_MAX      = 16777215
BC_SCALE_MAX    = 2147483647
BC_STRING_MAX   = 2147483647
MAX Exponent    = 9223372036854775807
Number of vars  = 32767

The maximum input base is 16.