What is the difference between Shell $* and $@

This article shows you the difference between Shell $* and $@. The content is concise and easy to understand. It will definitely brighten your eyes. I hope you can gain something through the detailed introduction of this article.

The difference between Shell $* and $@

When $* and $@ are not surrounded by double quotation marks, there is no difference between them, each parameter received is treated as a piece of data, separated by spaces.

But when they are enclosed in double quotes, there is a difference:

"$*" treats all parameters as a data as a whole, rather than each parameter as a data.

"$@" still treats each parameter as a piece of data, independent of each other.

For example, if five parameters are passed, for "$*", the five parameters will be merged together to form a piece of data, which can not be separated; for "$@", the five parameters are independent of each other. They are five pieces of data.

If you use echo to output "$*" and "$@" directly, you can't see the difference; but if you use a for loop to output data one by one, you can immediately see the difference.

For the use of for loops, please click: Shell for loops and for int loops

Write the following code and save it as test.sh:

#! / bin/bashecho "print each param from\"\ $*\ "" for var in "$*" do echo "$var" doneecho "print each param from\"\ $@\ "" for var in "$@" do echo "$var" done

Run test.sh with parameters:

[mozhiyan@localhost demo] $. . / test.sh a b c d

Print each param from "$*"

A b c d

Print each param from "$@"

A

B

C

D

From the running results, you can see that for "$*", it only loops once because it has only 1 point of data; for "$@", it loops five times because it has five pieces of data.

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