CODEWITHSUNDEEP
bash
Adooo
Adooo

Reputation: 670

What is the difference between assignment statement with echo statement in bash with multi command in oneline

I have two test snippet code, as follows:

# snippet code1
a=100 b=200                   # this line confuses me
echo $a                       # print "100"

# snippet code2
a=100 echo "sth else"         # this line confuses me
echo $a                       # print empty line

What is the difference? How to explain?

Thanks for your answer!

Upvotes: 0

Views: 83

Answers (1)

Benjamin W.
Benjamin W.

Reputation: 52506

The first one is multiple assignment statements on the same line; it's the same as

a=100
b=100
echo "$a

The second one is setting the environment for the command that follows; for example:

$ unset a
$ a=abc env | grep -w a
a=abc
$ declare -p a
-bash: declare: a: not found

The environment is set for just the command that follows.

Notice that

a=abc echo "$a"

doesn't work because the variable is expanded before the command is run.

Upvotes: 2

Related Questions