95 lines
3.1 KiB
Markdown
95 lines
3.1 KiB
Markdown
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# The `bc` command
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The `bc` command provides the functionality of being able to perform mathematical calculations through the command line.
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### Examples:
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1 . Arithmetic:
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```
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Input : $ echo "11+5" | bc
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Output : 16
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```
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2 . Increment:
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- var –++ : Post increment operator, the result of the variable is used first and then the variable is incremented.
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- – ++var : Pre increment operator, the variable is increased first and then the result of the variable is stored.
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```
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Input: $ echo "var=3;++var" | bc
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Output: 4
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```
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3 . Decrement:
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- var – – : Post decrement operator, the result of the variable is used first and then the variable is decremented.
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- – – var : Pre decrement operator, the variable is decreased first and then the result of the variable is stored.
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```
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Input: $ echo "var=3;--var" | bc
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Output: 2
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```
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4 . Assignment:
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- var = value : Assign the value to the variable
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- var += value : similar to var = var + value
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- var -= value : similar to var = var – value
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- var *= value : similar to var = var * value
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- var /= value : similar to var = var / value
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- var ^= value : similar to var = var ^ value
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- var %= value : similar to var = var % value
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```
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Input: $ echo "var=4;var" | bc
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Output: 4
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```
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5 . Comparison or Relational:
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- If the comparison is true, then the result is 1. Otherwise,(false), returns 0
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- expr1<expr2 : Result is 1, if expr1 is strictly less than expr2.
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- expr1<=expr2 : Result is 1, if expr1 is less than or equal to expr2.
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- expr1>expr2 : Result is 1, if expr1 is strictly greater than expr2.
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- expr1>=expr2 : Result is 1, if expr1 is greater than or equal to expr2.
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- expr1==expr2 : Result is 1, if expr1 is equal to expr2.
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- expr1!=expr2 : Result is 1, if expr1 is not equal to expr2.
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```
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Input: $ echo "6<4" | bc
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Output: 0
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```
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```
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Input: $ echo "2==2" | bc
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Output: 1
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```
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6 . Logical or Boolean:
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- expr1 && expr2 : Result is 1, if both expressions are non-zero.
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- expr1 || expr2 : Result is 1, if either expression is non-zero.
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- ! expr : Result is 1, if expr is 0.
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```
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Input: $ echo "! 1" | bc
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Output: 0
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Input: $ echo "10 && 5" | bc
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Output: 1
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```
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### Syntax:
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```
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bc [ -hlwsqv ] [long-options] [ file ... ]
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```
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### Additional Flags and their Functionalities:
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*Note: This does not include an exhaustive list of options.*
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|**Short Flag** |**Long Flag** |**Description** |
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|:---|:---|:---|
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|`-i`|`--interactive`|Force interactive mode|
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|`-l`|`--mathlib`|Use the predefined math routines|
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|`-q`|`--quiet`|Opens the interactive mode for bc without printing the header|
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|`-s`|`--standard`|Treat non-standard bc constructs as errors|
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|`-w`|`--warn`|Provides a warning if non-standard bc constructs are used|
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### Notes:
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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.
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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.
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