O'Reilly logo

Linux in a Nutshell, 6th Edition by Robert Love, Stephen Figgins, Ellen Siever, Arnold Robbins

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Name

let

Synopsis

let expressions
or
((expressions))

Perform arithmetic as specified by one or more expressions. expressions consist of numbers, operators, and shell variables (which don’t need a preceding $). Expressions must be quoted if they contain spaces or other special characters. The (( )) form does the quoting for you. For more information and examples, see Arithmetic Expressions in Arithmetic Expressions. See also expr in Chapter 3.

Examples

Each of these examples adds 1 to variable i:

i=`expr $i + 1`
let i=i+1
let "i = i + 1"
(( i = i + 1 ))
(( i += 1 ))
(( i++ ))

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required