It’s always nice to learn a new trick that may ever so slightly improve the way we use our tools. Today i learned two such little tricks regarding the command-line.

The first one is that, in Bash, we can do a sed-like substitution on the contents of a variable using the syntax ${var/pattern/substitution}.

As a toy example, consider converting a Reddit URL to the old (and arguably better) version of the site:

$ url=""
$ echo ${url/reddit/old.reddit}
$ xdg-open ${url/reddit/old.reddit}

This seems like a more convenient way of doing simple text replacements than having to pipe things to a sed subprocess.

And there’s a lot more to Bash’s cryptic but powerful ${} syntax: case conversion, substring slicing, you name it. The manpage has a thorough description under the “Parameter Expansion” heading:

man bash | less -p "Parameter Expansion"

Which, by the way, demonstrates the second of today’s tricks: we can use the -p (or --pattern) argument in less to scroll directly to the first occurrence of a given pattern.

I doubt that i’ll be using this one often, as it seems more convenient to search for the pattern interactively using / when already inside of less instead. But i can imagine using it as a neat “documentation pointer” to share a less command with others, just like the above snippet was handed to me :)

Thanks to my friend —and seasoned Linux geek— @racter for showing me these two tricks. I found them quite neat and maybe worth sharing. Or at least, worth using as an excuse to finally start writing a blog, which, here it is! So, hello world! 👋