Which Linux command or utility is simple, powerful, and surprisingly unknown to many people or used less often?
This could be a command or a piece of software or an application.
For example I’m surprised to find that many people are unaware of Caddy, a very simple web server that can make setting up a reverse proxy incredibly easy.
Another example is fzf. Many people overlook this, a fast command-line fuzzy finder. It’s versatile for searching files, directories, or even shell history with minimal effort.
socat- connect anything to anythingfor example
socat - tcp-connect:remote-server:12345socat tcp-listen:12345 -socat tcp-listen:12345 tcp-connect:remote-server:12345nmap *your_local_ip_address*for example
nmap 192.168.1.43/24will show you what devices are connected to the local network, and what ports are open there. really useful, for example, when you forgot the address of your printer or raspi yet again.you can also use it to understand what ports on your computer are open from an attacker’s perspective, or simply to figure out what services are running (ssh service).
losetupit’s useful for dealing with virtual disk images. like a real physical hard disk, but it’s a file on the computer. you can mount it, format it, and write it to a real physical disk.
it’s sometimes used with virtual machines, with iso images, or when preparing a bootable disk.
netstat -tunlshows all open ports on the machine to help diagnose any firewall issues.Not powerful, but often useful,
column -taligns columns in all lines. EG$ echo {a,bb,ccc}{5,10,9999,888} | xargs -n3 a5 a10 a9999 a888 bb5 bb10 bb9999 bb888 ccc5 ccc10 ccc9999 ccc888 $ echo {a,bb,ccc}{5,10,9999,888} | xargs -n3 | column -t a5 a10 a9999 a888 bb5 bb10 bb9999 bb888 ccc5 ccc10 ccc9999 ccc888Control+r == search through your bash history.
I used linux for ten years before finding out about that one.
xargs
Man
probably well known at this point but rsync is incredible and I use it all the time
batcat
It’s like cat but better. Great for when you just want to look at the contents of a file, without loading a whole text editor.
Oh also, tldr
My procedure for learning how to use a cli command goes tldr page -> --help if the tldr fails to help me -> THEN the full manpage
bcIt’s a simple command line calculator! I use it all the time.
Very useful for shell scripts that need to do maths as well. I use it to make percentages when stdout has values between 0.0 and 1.0
jq - super powerful json parser. Useful by hand and in scripts
I love jq, but I wouldn’t call it “surprising simple” for anything but pretty-formatting json. It has a fairly steep learning curve for doing anything with all but the simplest operations on the simplest data structures.
It’s not even pretty or accessible. 2-spaced indentation is incredibly hard to read.
It can also format minimized JSON from cURL API requests
Combine with jc to process CSV files. This is how I get data into my plain text accounting system.
jqandyqare both things I install on pretty much every machine I have.
motion
After spending years dealing with shady freeware and junk software on windows, I was floored by how easy and nonchalantly I was able to set up a simple security camera on my PC
kde connect
yesThe most positive command you’ll ever use.
Run it normally and it just spams ‘y’ from the keyboard. But when one of the commands above is piped to it, then it will respond with ‘y’. Not every command has a true -y to automate acceptance of prompts and that’s what this is for.
Also, you can make
yesreturn anything:yes noI… did not know that. Thanks, TIL!
What’s the syntax here? Do I go
command && yes
I’m not sure if I’ve had a use case for it, but it’s interesting.
Also my favourite way to push a core to 100% CPU
yes > /dev/nullhow is that better than
cat /dev/zero > /dev/nullor
while true; do :; doneWho said it was better? It’s just my favourite.
Like my favourite shirt, it’s no better than the others, but it brings me a little joy :)
- on a serious note though, thank you for sharing your two examples - I didn’t know they existed.
That will just wait for
commandto finish properly and then runyes.What you want to run is
yes | command, so it spams the command with confirmations.truedelivers error level 0,falseerror level 1.yes && echo True || echo Falsewill always be True.false && echo True || echo Falsewill always be False.Common usage is for tools that ask for permissions and similiar.
yes | cp -ihas the same effect ascp --force(-i: prompt before overwrites).Sorry, I should have explained that. it’s
command | yesyes|command- Eg,yes|apt-get update(Not a great example since apt-get has -y, but sometimes that fails when prompting for new keys to accept)Edit: I got it backwards, thanks @lengau@midwest.social for the correction.
You’ve got it backwards - you need to pipe the output of
yesinto the input of the command:yes | command-that-asks-a-lot-of-questionsSo I did - thanks for the correction, edited.
For some cases I use “|| true”.
The idiom accepts that the preceding command might fail, and that’s OK.
For example, a script where mkdir creates a directory that might already exist.
mkdir -pwill not complain if the dir exists
