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:12345Pandoc.
nmap *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 ccc888wait, shell could make matrix multiplication ?
No, that’s just brace expansion.
xargs
Very true. I used to do magic with xargs when working as a sysadm. Also a good way to mess up on a grand scale. Ask me how I know.
So, how do you know?
Control+r == search through your bash history.
I used linux for ten years before finding out about that one.
Works much better with fzf, but even just default bash it’s useful.
So did I until reading this post. Thanks!
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
I like batcat aka bat, but nominate the humble ‘cat’ instead.
Want to copy a disk image to a device? You can use cat for that:
cat file.iso>/dev/sdfWhat to copy local stdout over ssh? Use cat.
ls -l | ssh myhost 'cat >out.txt'That’s simple and surprisingly powerful.
Man
dude
Bruh
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
I once wrote a bc script that calculated parameters for the Blackman window for a FIR filter. (Had formulas already so not that impressive) Upped the precision until it needed like 30 sec to calculate, completely unnecessarely :).
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
jqandyqare both things I install on pretty much every machine I have.Combine with jc to process CSV files. This is how I get data into my plain text accounting system.
ip eg:
# ip a # ip a a 192.168.1.99/24 dev enp160The first incantation - ip address (you can abbreviate whilst it is unambiguous) gets you a quick report of interfaces, MAC, IPs and so on. The second command assigns another IP address to an interface. Handy for setting up devices which don’t do DHCP out of the box or already have an IP and need a good talking to.
Oh and you can completely set up your IP stack, interfaces and routing etc with it. Throw in nft or iptables (old school these days - sigh!) for filtering and other network packet mangling shenanigans.
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
When you’re ready for a full monitoring package, check out Frigate.
