mkdir if not exists

To create new directories if they do not exist and ignore the command if they do (no error message) use: 

 $ mkdir -p 
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The -p flag also allows for subdirectories to be created, if they do not already exist. For example:

 $ mkdir -p foo/bar/test
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will create the folder “test” within the folder “bar” within the folder “foo”. 

When should I use mkdir vs mkdir -p?

mkdir -p can handle creating subdirectories in one command. An additional feature of adding the -p flag is the lack of an error message when the directory already exists. For example, to create subdirectories using mkdir you would need to do:

 $ mkdir foo #create the folder “foo”
 $ cd foo #navigate into the folder “foo”
 $ mkdir bar #create the folder “bar” inside the folder “foo”

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adding the -p flag allows you to create the subdirectory bar inside the directory foo (even if foo doesn’t exist yet) in one line:

 $ mkdir -p foo/bar #creates the folder foo and the folder bar inside foo

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Using mkdir -p to ignore a directory if it already exists

Without -p, mkdir has this behavior:

 $ mkdir foo #create foo
 $ mkdir foo #foo exists now, command errors out

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will return the error, “File exists”. But, when used in conjunction with the -p flag, the command to create a new directory is instead ignored, with no error returned:

 $ mkdir -p foo #create foo
 $ mkdir -p foo #foo exists now, command is ignored

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So mkdir -p is useful if you want to make subdirectories quickly, and when using the mkdir command in situations where you want the command to be ignored (no error) if the directory already exists – for example, when using mkdir in combination with other commands to create efficient pipelines for data writing and storage.

Create directory if missing while using cp

mkdir -p can be useful in combination with other commands like cp (copy). Combining the mkdir and cp commands is a powerful way to create directories that don’t exist and copy them over all in one go:

 $ mkdir -p  && cp 

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where the && operator combines the two commands, and the cp command stands for “copy”.