Fish Shell:
Creating a temporary file

How to:

In Fish Shell, you can create a temporary file using mktemp. Here’s a quick example:

set tempfile (mktemp)
echo "Hello, temporary world!" > $tempfile
cat $tempfile
rm $tempfile

And you’ll see something like this:

Hello, temporary world!

This creates a temporary file, writes a line to it, displays the content, and then deletes the file.

Deep Dive

Back in the day, temporary files were often created manually, leading to potential naming conflicts and security issues. mktemp to the rescue! This command creates a file with a unique name, reducing the risk of file collision.

Alternative methods include writing to /dev/shm on Linux or using memory-based file systems. However, these methods are not as portable as mktemp.

As for temporary files’ lifetimes, it’s vital to remember that they should be deleted by the program that creates them. This ensures no leftover files consuming system space. In some systems, the /tmp directory gets cleared on reboot, but you shouldn’t rely on this behavior for cleanup.

See Also

• Fish Shell Documentation: https://fishshell.com/docs/current/
• mktemp Manual: https://www.gnu.org/software/autogen/mktemp.html
• Filesystem Hierarchy Standard: https://refspecs.linuxfoundation.org/FHS_3.0/fhs/index.html