dc  macOS
Overview
The dc
(desk calculator) command is a reverse Polish notation (RPN) calculator that operates on arbitrary precision numbers. It is typically used for performing mathematical operations in scripts or command line sessions where complex, precise computation is required. It supports a variety of operations, including addition, subtraction, multiplication, division, exponentiation, and modulo operations. dc
is particularly effective for handling very large numbers and for scripting complex calculations that require conditional processing and loops.
Syntax
dc [options] [file...]
The dc
command can be used in interactive mode or can execute commands from a file or standard input. Multiple files can be specified, and they will be processed in order.
Expressions:
Expressions in dc
are written in postfix notation, where the operator follows all operands, e.g., 5 3 +
to add 5 and 3.
Options/Flags

e, –expression=SCRIPT
Allows you to specify the script directly on the command line. Multiplee
options can be chained together. 
f, –file=FILE
Specifies a file from whichdc
reads more commands. Multiplef
options can be used to read multiple files. 
h, –help
Displays help information and exits. 
V, –version
Outputs version information and exits.
Examples

Basic Arithmetic Operations:
echo "5 3 + p"  dc
This example adds 5 and 3 and prints the result, which will output
8
. 
Using Files:
echo "6 2  p" > calculation.dc dc calculation.dc
This saves the subtraction operation in a file and then computes the result using
dc
, which will output4
. 
Chaining Expressions:
dc e "12 8  p" e "14 3 * p"
This will perform a subtraction and a multiplication, outputting
4
and42
respectively.
Common Issues
 Syntax Errors: Incorrect command sequence or mixing up the postfix notation can lead to errors. Always check that your operators follow the correct sequence of operands.
 Division by Zero: This will cause an error in
dc
. Ensure that your scripts check for zero divisors as part of their logic.
Integration
dc
can be integrated with shell scripts to perform dynamic calculations. Here’s an example of using dc
with bash
to calculate factorial:
factorial() {
echo "$1 1  p"  dc e '
[q]sQ
[1 1]s:sl
[ldl1dslx*]dsfx
lQx
'
}
factorial 5
This calculates the factorial of 5 by recursively multiplying numbers.
Related Commands
bc
– An arbitrary precision calculator language.expr
– Evaluate expressions and perform arithmetic operations in shell scripts.
For further reading and more detailed information, consult the dc
man page by running man dc
on your terminal, or visit the online manual pages provided by GNU or other similar resources.