I’ve been homelabbing for a few years now, and recently I’ve really been focusing in on learning how to use gnu/linux. I thought it might be fun to periodically share the things I’ve been learning. The stand outs for me this past week were:
- Use the full path when referencing files and directories in bash scripts (Edit: when it makes sense, which is something I’m also still learning. This mkaes sense when the files will always be located in the same place.)
- In a bash script, the variable
${file##*/}will get you the name of the file your script is handling (example, when looping over files in a directory. I believe that’s a shell/bash standard variable, but I need to learn where it came from and how it works) - Ubuntu gets a ton of justifiable criticism, but I find Canonical’s Multipass to be a great tool for spinning up Linux virtual machines. Especially on Apple silicon macs.
- Piping the output of
lstogrepas a variable in a path is a great way to change to a directory you know exists but can’t remember the exact name of. (Example:cd ~/movies/“$(ls ~/movies | grep movie-name)”) - The reason Mac cli utilities have syntax variations compared to the standard gnu/linux utilities is because macOS and its cli utilities are BSD based. This was information I knew at a high level, but had never really understood the implications of until this week.
- Related to point 5, if you’re on macOS trying to learn and you’re annoyed by the syntax differences between bsd and gnu utilities, you can run this script from darksonic37 on github to remove the bsd utilities from macOS and replace them with their gnu counterparts. (I have not run or reviewed the script. I found mulitpass first, and so far I’m happy using the Ubuntu virtual machine)
Regarding some of your points:
##deletes the longest match from the beginning, so it deletes everything to the last slash, as the asterisk expands as far as possible. If you wanted the directory the file is in using this method, you'd use${file%/*}. This deletes the shortest match from the end. You also have the dedicated commandsbasenameanddirnamefor this.Instead of cd into output of ls | grep I'd suggest you to install fzf and fuzzy find directories to cd into.
I didn’t know that tool existed I will give fzf a try!
To expand a little on @Laser ‘s point 2:
In bash (and other programming languages) # is used at the start of the line to notate comments.
When writing percentages, you write the symbol after the number, e.g. 50%
That’s how I keep them apart, lol
Theres a section in the bash manual with these and a whole bunch of more expansion tricks.
One I find useful is
That’s a super useful way to remember. Thank you!