explain $(1) $@ in makefile based on examples
时间: 2024-02-17 07:03:53 浏览: 20
In a Makefile, `$(1)` and `$@` are special variables that are used to represent arguments and targets, respectively.
Here's an example of how `$(1)` can be used in a Makefile:
```
define my_rule
echo $(1)
endef
all:
$(call my_rule, "Hello, world!")
```
In this example, we define a new variable `my_rule` that contains a shell command to print the value of `$(1)`. The `$(call)` function is used to call the `my_rule` variable with the argument `"Hello, world!"`. When we run `make all`, the output will be:
```
echo "Hello, world!"
"Hello, world!"
```
Here's an example of how `$@` can be used in a Makefile:
```
all: hello.txt
hello.txt:
echo "Hello, world!" > $@
```
In this example, we define a rule to create a file `hello.txt` that contains the text "Hello, world!". The `echo` command is used to write the text to the file, and the `$@` variable is used to represent the target `hello.txt`. When we run `make all`, the output will be:
```
echo "Hello, world!" > hello.txt
```
And the file `hello.txt` will be created with the text "Hello, world!" in it.
So, `$(1)` is used to represent arguments in a Makefile, and `$@` is used to represent the target of a rule.