Accessing newest file in a directory

Posted on April 18, 2021

There are many instances where I want to access the most recent file in a directory:

By default, my browser saves PDF files (and other downloaded files, for that matter) in ~/Downloads. Rather than navigating to a more appropriate directory via the GUI, I find it more convenient to cd to the appropriate directory on the command line (where zoxide is an amazing tool to jump to commonly used directories) and simply move the file there.
I use a browser plugin to convert long web articles to .epub so that I can read them later on my eInk tablet. This plugin saves files in ~/Downloads and has no option to change the downloads directory.
I run a cron script that downloads and packages the latest version of ConTeXt by running makepkg in a directory containing the PKGBUILD file for luametatex. However, I don’t automatically upgrade the package. I always prefer to upgrade packages manually when I know that I have the time to fix the upgrade if something breaks (happens rarely, but I don’t want something to break half an hour before a deadline). When updating, I want to find the latest luametatex-date.pkg.tar.gz file in the directory.

I recently discovered glob qualifiers, which is perfect for these tasks. In the shell * expands to all files and directories. Zsh has options to qualify which files needs to be expanded. In particular:

*(.) expands all files (i.e., excludes directories)
*(.om) expands all files and sorts them descending order according to modification time
*(.om[1]) selects the first such file.

Thus, for my first two use cases, I can use:

z desired-directory && mv ~/Downloads/*(.om[1]) ./

For the third use case:

z luametatex && sudo pacman -U *(.om[1])

Sometimes, I want to use the latest file matching a particular pattern (say, the latest PDF file with pattern in the title). In such cases, I can use:

mv ~/Downloads/*pattern*.pdf(om[1]) ./

Or, if I want to see the name of the file before moving it:

mv ~/Downloads/*pattern*.pdf^Xm

(where ^Xm means press CTRL+X m). Search for _most_recent_file in zshcompsys for details.

This entry was posted in Terminal and tagged zsh, glob qualifiers, zshexpn.