Notes on "bc"

Brian

Contents

-s,--standard  Adhere to the POSIX standard
-l,--mathlib   Add a math library, set SCALE to 20

Names begin with a letter and may be followed by [[:alnum]_]*
Four special variables:
SCALE defines how some operations use digits after the decimal point
IBASE is the conversion base for input numbers
OBASE is the conversion base for output numbers
LAST is a variable that has the value of the last printed number (an extension)
Output is generated by deliberately not assigning the result of a calculation to a variable.

bc uses /* ... */ style comments. As an extension, # is a commment if it’s a the start of a line (after whitespace)

Directly from the Wikipedia page

+     -     *     /
+=    -=    *=    /=
++    --    <     >
==    !=    <=    >=
( )   [ ]   { }

Modulus operators % and %= work, but SCALE should be set to 0 first.

PI=”$(echo “scale=20; 4*a(1)” | bc)” echo $PI

Built-in:

From the library:

See the man page

About