Bash shell option -r-CodePudding

I am no expert in shell scripts and as I read one of the lines in a bash script, I see this:

if [[ ! -r test.json ]]
then
    printf "no test.json here\n" >&2
    exit 1
fi

What does the line if [[ ! -r test.json ]] option do? From the logic, it seems like it checks if the file test.json does not exist. I did some research to see what all options are indeed provided in a shell command, but I don't see the -r option here: https://tldp.org/LDP/abs/html/options.html

CodePudding user response：

-r is one of many possible arguments for the [-program and the [[ bash construct (which is what you're using here).

-r checks if the argument that follows it is a file, it exists, and it's readable.

A bash cheatsheet can be useful for these things while making shell scripts

CodePudding user response：

You're looking in the wrong part of the documentation. It's not a shell option, it's a conditional expression operator.

-r file
True if file exists and is readable.

The ! operator inverts the condition, so this tells you if test.json doesn't exist or is not readable.