The bc command¶

The bc command provides the functionality of being able to perform mathematical calculations through the command line.

Examples:¶

1 . Arithmetic:

Input : $ echo "11+5" | bc Output : 16 2 . Increment: - var –++ : Post increment operator, the result of the variable is used first and then the variable is incremented. - – ++var : Pre increment operator, the variable is increased first and then the result of the variable is stored.

Input: $ echo "var=3;++var" | bc Output: 4 3 . Decrement: - var – – : Post decrement operator, the result of the variable is used first and then the variable is decremented. - – – var : Pre decrement operator, the variable is decreased first and then the result of the variable is stored.

Input: $ echo "var=3;--var" | bc Output: 2 4 . Assignment: - var = value : Assign the value to the variable - var += value : similar to var = var + value - var -= value : similar to var = var – value - var *= value : similar to var = var * value - var /= value : similar to var = var / value - var ^= value : similar to var = var ^ value - var %= value : similar to var = var % value

Input: $ echo "var=4;var" | bc Output: 4 5 . Comparison or Relational: - If the comparison is true, then the result is 1. Otherwise,(false), returns 0 - expr1<expr2 : Result is 1, if expr1 is strictly less than expr2. - expr1<=expr2 : Result is 1, if expr1 is less than or equal to expr2. - expr1>expr2 : Result is 1, if expr1 is strictly greater than expr2. - expr1>=expr2 : Result is 1, if expr1 is greater than or equal to expr2. - expr1==expr2 : Result is 1, if expr1 is equal to expr2. - expr1!=expr2 : Result is 1, if expr1 is not equal to expr2.

Input: $ echo "6<4" | bc Output: 0 Input: $ echo "2==2" | bc Output: 1 6 . Logical or Boolean:

• expr1 && expr2 : Result is 1, if both expressions are non-zero.
• expr1 || expr2 : Result is 1, if either expression is non-zero.
• ! expr : Result is 1, if expr is 0.

``` Input: $ echo "! 1" | bc Output: 0

Input: $ echo "10 && 5" | bc Output: 1 ```

Syntax:¶

bc [ -hlwsqv ] [long-options] [ file ... ]

Additional Flags and their Functionalities:¶

Note: This does not include an exhaustive list of options.

Notes:¶

1. The capabilities of bc can be further appreciated if used within a script. Aside from basic arithmetic operations, bc supports increments/decrements, complex calculations, logical comparisons, etc.
2. Two of the flags in bc refer to non-standard constructs. If you evaluate 100>50 | bc for example, you will get a strange warning. According to the POSIX page for bc, relational operators are only valid if used within an if, while, or for statement.