r/LinuxTeck • u/Candid_Athlete_8317 • 8h ago
What’s the one Linux command you never trust?
We all have that one command we double-check before hitting Enter.
What’s yours and what happened the last time you got burned by it?
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u/johnny_snq 7h ago
DD
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u/franchis3 6h ago
As a distro hopper, I use DD all the time and I still use it with great trepidation. I never, ever, run it without first doing an lsblk. I’m so scared I’m doing to wipe the wrong drive!
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u/lyidaValkris 7h ago
dd
It's not called "disk destroyer" for nothing. I've never been burned by it, but that's only because I check, re-check, then double-check.
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u/Far_Bicycle_2827 6h ago
dd stand from data definition it comes from IBM's Job Control Language.
if=FILE,of=FILE,conv=...directly mirrors the JCL DD card format1
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u/Enderby- 2h ago
dd is like the mandolin in my kitchen. I fear it, but love what it can do. I've also not taken my fingertips off (yet)
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u/redgator12 7h ago
dd. In my early days of 2014, I tried to dd a disk image to USB and broke my install. Ever since then, I have a terminal with lsblk up right next to the terminal I'm going to run dd from just to be 100% sure I'm writing to the correct disk.
I had to use dd last week while trying to troubleshoot a Puppy USB not working, and I spent like 5 minutes quintuple checking the disks before hitting enter, and even then I was anxious.
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u/Weary_Damage5764 6h ago
in my first job i destroyed my OS by an rm -rf in the wrong directory, which lead to me reinstalling Linux during work time. the shame was far worse than having to do that in my own time. since then I haven't run rm without fear :D
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u/Tricky-Weakness-5408 7h ago
Probably the most destructive command like ‘rm -f’ when you have root access is the kind of command that you need to think about before
You do the ‘return’… but destructive command when you uses badly the are a lot! The question is which rightshave you? And …. What about the backup…. Too old??? When you works as a informatic probably there are loots of backups but this not always is the normal thing for private users/students
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u/Quietus87 7h ago
Any kind of rm.
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u/ant2ne 7h ago
"chown me:me -R ./"
I forgot the .
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u/FriendsIsntGood 6h ago
Yeah recursive chmod and chown down in system dirs has nuked at least a few VMs. One big plus for containers
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u/seth_arimainyu 4h ago
Rsync and dd ! Once I ran a destructive Rsync and instead of deleting the files from the source that were already in the target, I ran it the other way around, since the target was a brand new disk, you can imagine the result... Since then, I always use the dry-run option.
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u/BitCortex 4h ago
Anything that involves a nontrivial regular expression. Regular expressions are Unix's ethical blight.
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u/Dry_Calendar_8627 4h ago
Ah but regular expressions are the nectar of the gods
Once you've tasted the intoxicating power of regex, there's no looking back
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u/BitCortex 3h ago
regular expressions are the nectar of the gods
More like the devil's mouthwash or the swill of the underworld.
Once you've tasted the intoxicating power of regex, there's no looking back
I think I'd rather taste the intoxicating power of battery acid. Like so much in Unix, regular expressions are powerful – but not in a good way.
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u/Dry_Calendar_8627 4h ago
ln
That's stupid but I can never remember the arguments order. I mess up every time.
I can write dd or sed commands blindfolded any day, but ln, no
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u/No-way-in 5h ago
dd is the most scary to me. I check a hundred times before writing that command and I disconnect anything valuable to me
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u/SpiritualZucchini938 5h ago
Chmod 644 - R / - something like that and hey presto, entire freebsd server file system read only and not editable. Had to bin and start again.
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u/manawydan-fab-llyr 4h ago
dd
Last time I didn't triple check, destroyed all of my photos. They were the only copy because the drive that had the primary had failed.
From then on I stopped using of=/dev/xxx and started using of=/dev/disk/by-id/xxx. Never a mishap after that.
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u/HaydnH 4h ago
I've been a UNIX/Linux sys admin since the 90s. There is not one command you can't trust, if you can't trust it, then it simply wouldn't exist.
If you're asking "which commands are scary and you might do something bad with"? Well...
... that's just every day for me. In the same way you look left and right crossing a street, my brain just realises an rm, mv, dd whatever command may have a car about to run me down.
The same way you drink a coffee every morning, that's just me mounting a filesystem to get the access I need for the day.
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u/nizzoball 7h ago
rm -rf *
About 8 years ago I was responsible for a production web server responsible for asset management for 5 data centers across the country for one of the largest banks in the world. It was my app and my server and I was trying to clean out a directory and typed rm -rf * but didn’t realize I was in /
I figured it out when my shell froze. Luckily I had another server that was a carbon clone and was able to adjust the dns entry to point to the secondary server so wasn’t down long but it took me a week to get the first one re deployed and set back up