CODEWITHSUNDEEP
makefile
storen
storen

Reputation: 1035

Variable expansion in Makefile

It's part of code in a makefile, there are two $$ to expand variable CONTINUE,why? Are there any special meaning?

read -r -p "Overwrite your existing default nginx configuration? [y/N] " CONTINUE; 
    if [ "$$CONTINUE" == "y" ] || [ "$$CONTINUE" == "Y" ]; then 
        echo "y"
    else 
        echo "n"
    fi

Upvotes: 0

Views: 353

Answers (1)

Naga
Naga

Reputation: 128

$$ is (simply put) escaping in a Makefile because $-Vars also exists there. To use the variable for bash (which also needs $var) you have to write $$

pre edit (topic changes from "script" to "makefile")

Does this script even work?

# ./test.sh
Overwrite your existing default nginx configuration? [y/N] y
n

Change it to a single $.

$$ expands to the PID of the executing bash shell

($$) Expands to the process ID of the shell. In a () subshell, it expands to the process ID of the invoking shell, not the subshell.

Bash ref

Upvotes: 1

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