010-160 Question #87: Real Exam Question with Answer & Explanation

The correct answer is E. USERNAME=bob. Shell variable assignment in bash uses the syntax NAME=value with no spaces around the equals sign and no keyword prefix.

The Power of the Command Line

Question

Which of the following commands sets the variable USERNAME to the value bob?

Options

Aset USERNAME bob
B$USERNAME==bob
Cvar USERNAME=bob
DUSERNAME==bob
EUSERNAME=bob

Explanation

Shell variable assignment in bash uses the syntax NAME=value with no spaces around the equals sign and no keyword prefix.

Common mistakes.

A. The set command is used to set shell options or positional parameters, not to assign named variables - this syntax is invalid for variable assignment.
B. Prefixing a variable name with $ dereferences it for reading its value; using == is a comparison operator, making this an invalid assignment expression.
C. The var keyword is used in JavaScript and is not valid shell syntax for variable assignment in bash or POSIX shells.
D. The == operator performs comparison, not assignment - this expression does not set any variable value.

Concept tested. Bash shell variable assignment syntax

Reference. https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameters

Topics

#shell variables#variable assignment#bash syntax

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