The mktemp command creates a temporary file and prints its name on stdout. Temporary files are created by default in the /tmp directory.

The syntax of creating a temporary file is as follows:

$ mktmp
/tmp/tmp.xEXXxYeRcF

A file with the name tmp.xEXXxYeRcF gets created into the /tmp directory. We can further read and write into this file in an application for temporary use. Using the mktemp command instead of using a random name for a temporary filename avoids accidental overwrite of an existing temporary file.

To create a temporary directory, we can use the -d option with mktemp:

$ temp_dir=mktemp -d
$ echo $temp_dir
/tmp/tmp.Y6WMZrkcj4

Furthermore, we can explicitly delete it as well:

$ rm -r /tmp/tmp.Y6WMZrkcj4

We can even specify a template to use for a temporary file by providing an argument as name.XXXX. Here, name can be any name by which a temporary file should begin, and XXXX tells the length of a random character to be used after a dot (.). In general, while writing an application if temporary files are needed, the application name is given as the temporary file name.

For example, a test application needs to create a temporary file. To create a temporary file, we will use the following command:

$ mktemp test.XXXXX
test.q2GEI

We can see that the temporary file name begins with test and contains exactly five random letters.