Xargs tips
After 12 years being a Windows admin, I've now used powershell more than other languages so I'm pretty fluent in it's syntax. So it makes me happy when I stumble upon bash/linux scripting paradigms which have been brought over to powershell.
It's great to see the inspiration powershell has gained from Unix systems and also great that it makes it easier for me to remember.
One paradigm I that I wished bash/*nix had is the Foreach-Object command.
It makes working on collections of objects a breeze. I often find myself
scratching my head when trying similar tasks on *nix. Enter xargs
Take this simple situation: I have a directory and I want to delete everything bar a single .config file.
$ ls -a
. blog.css .entry-23032.md .footer.html main.css
.. .config .entry-23032.md.swp .header.html .title.html
My powershell brain wants to:
$ gci | ? Name -ne '.config' | foreach-object { rm $_ }
On *nix, Xargs is a bit like adding pipeline input to rm
$ ls -a | grep -v '\.config' | xargs rm
xargs is going to automatically append the output of the previous command as
an argument of the rm command. In this case the argument has to be the final
argument, but that can be changed using the -I parameter which specifies a
substitue variable
$ ls -a | grep -v '\.config' | xargs -I '{}' echo "Delete {} ?"
Of course the powershell line could be a bit shorter
$ gci | ? Name -ne '\.config' | rm
If you have any comments or feedback, please email me and let me know if you will allow your feedback to be posted here.
Tags: bash-v-powershell, xargs, bash, powershell