What is the base value for arithmetic expansion in Bash?
The base must be a decimal between 2 and 64 representing the arithmetic base. The default base value used in bash arithmetic expansion is the base 10. Note that, you can also prefix numbers with a leading zero 0 to represent octal numbers (base 8). A leading 0x or 0X would be interpreted as an hexadecimal.
When to use the builtin shell expansion in Bash?
The builtin shell expansion allows you to use the parentheses ( (…)) to do math calculations. The format for the Bash arithmetic expansion is $ ( ( arithmetic expression )). The shell expansion will return the result of the latest expression given.
Is there a way to do math calculations in Bash?
The legacy way to do math calculations with integer, and only integer, has been for a long time to use the expr command line. Though, this method can be slow as expr is a binary, not a shell builtin. It will fork a new process which is not ideal in a large for-loop. Also, the expr behavior may vary between systems depending on the implementation.
How is a mathematical constant interpreted in Bash?
Mathematical constants are simply fixed values you write: 1, 3567, or 4326. Bash interprets some notations specially: #… is interpreted as a number according to the specified base , e.g., 2#00111011 (see below) this is interpreted as an octal value.
When does expending a variable lead to an arithmetic error?
When a variable is expended to represent a number with leading zeros and composed with numbers equal or above 8, it will lead to a bash arithmetic error like bash: 08: value too great for base (error token is “08”).
When to remove leading zeroes from a variable in Bash?
When a variable is expended to represent a number with leading zeros and composed with numbers equal or above 8, it will lead to a bash arithmetic error like bash: 08: value too great for base (error token is “08”). To prevent such issues, you must remove the leading zeroes on the variable before doing the Arithmetic Expansion.
How to calculate a floating point precision in Bash?
You can calculate a floating-point precision percentage in Bash using the printf method and Arithmetic Expansion, or you can calculate a rounded integer percentage using Arithmetic Expansion with the ( (…)) notation. The round-up approach leverages the shell behavior to round toward zero (0).
How to zero pad a sequence of integers in Bash?
This way you can avoid using an external program seq which is NOT available on all the flavors of *nix. I pad output with more digits (zeros) than I need then use tail to only use the number of digits I am looking for.