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docs/Linux-Commands/.recycle/009-the-bc-command.md

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+# 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.*
+
+|**Short Flag**   |**Long Flag**   |**Description**   |
+|:---|:---|:---|
+|`-i`|`--interactive`|Force interactive mode|
+|`-l`|`--mathlib`|Use the predefined math routines|
+|`-q`|`--quiet`|Opens the interactive mode for bc without printing the header|
+|`-s`|`--standard`|Treat non-standard bc constructs as errors|
+|`-w`|`--warn`|Provides a warning if non-standard bc constructs are used|
+
+### 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.