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Linux Command One-Liners

338 points by arkj 6y ago

j0057 6y ago
Using conditional includes in your global gitconfig based on the path is a much less error prone way of having different identities for different projects. https://www.motowilliams.com/conditional-includes-for-git-config https://www.motowilliams.com/conditional-includes-for-git-co...
wruza 6y ago
>_ This part will likely confuse people who are not familiar with shell and will create a bunch of thousands "_" files worldwide. Quick explanation: >_ echo hello or equivalently: echo hello >_ when executed in a shell creates a file named "_" with contents of "hello". Author seems to use ">_" as a terminal icon, but many will copy it as part of a command. That is, if I'm not missing anything clever here. Upd: copy button doesn't copy the >_ part, so the "icon" theory seems to be correct.
- 0xf8 6y ago
  also it’s called a shell prompt for what it’s worth.
- kps 6y ago
  A ‘trick’ for fancy prompts containing information is to give them the form, : all the stuff; As long as ‘all the stuff’ is parseable as shell words (which you can ensure by quoting with printf '%q' if there's doubt), then you can copy and paste entire lines. The trivial copyable prompt would be :;
  - chrisweekly 6y ago
    Thank you for this!! TIL. Immediately adopting. Now wishing everyone else knew this too.
    - kps 6y ago
      I read about this long ago, possibly in the Blit era, possibly in ;login: (other order, other reasons). It's old lore, but not widely known, so I try to mention in when the subject of prompts comes up.
  - Arnavion 6y ago
    Note that this isn't guaranteed to be a no-op for arbitrary "all the stuff". Specifically it won't work for commands involving pipes, or commands involving command substitution / process substitution. That is: : bar "$(foo)" : bar <(foo) : < <(foo) bar : bar | foo will all still execute `foo`
    - kps 6y ago
      That's why I mentioned quoting.
- loudmax 6y ago
  Agreed, including the ">_" prompt in the command line isn't really helpful. The copy icon works, it's extra unnecessary cognitive overhead. Also, ">_" is an unusual prompt, I don't know what distro ships with that by default.
  - LukeShu 6y ago
    ">" is the prompt on MS-DOS, and "_" is the cursor. Somehow this has resulted in ">" or ">_" being the terminal "icon" even in unixy parts of the world; looking at the generic "utilities-terminal" icon: the default theme for Gnome 3 ("Adwaita") uses ">_" in the icon, the default theme for KDE ("Breeze") uses ">", and the runner-up ("Oxygen", which also comes bundled with KDE), also uses ">_".
    - scarmig 6y ago
      Also, the SSH app on Chromebooks.
    - marcosdumay 6y ago
      That's unfortunate, because on Linux the shells tend to use ">" for a continuation prompt, where you can not enter complete commands.
- tasuki 6y ago
  Yes, I wonder what benefit there is to include `>_` as the prompt. The obvious drawback is confusing some poor souls. Also it's ugly, who would want to use `>_` as their prompt?
- roosgit 6y ago
  It could have at least a less prominent color. And it could be added with a `::before` pseudo-element so you can't select it (just for decoration). Might be also annoying for screen readers without `aria-hidden`.
- bluedino 6y ago
  Am I some sort of weirdo because I don't recall seeing >_ used before as a prompt?
  - prionassembly 6y ago
    _ is the blinking cursor. Prompt is just >
    - bluedino 6y ago
      But it doesn't blink.... > is kind of and odd prompt as well.
      - wruza 6y ago
        I think it is from the dos/windows world. A:\>_
        pbhjpbhj 6y ago
        Or Acorn Electron BASIC >_ or whatever, it's a standard prompt if you're old enough!
      - nulbyte 6y ago
        That is a default in some current and old Unix systems, as well as the tcsh shell.
- tomcooks 6y ago
  the author should hide that "> _" by including it as a CSS :before or :after content, which by definition is not selectable.
  - skinnyasianboi 6y ago
    Author of linuxcommandlibrary.com here. I did a quick fix and replaced ">_" with "$". I will dig into CSS :before during the next update. Thanks for the idea.
- skinnyasianboi 6y ago
  Author of linuxcommandlibrary.com here. You are 100% right. That was quite dump. I think I got the idea from the SSH icon I used in the basics page. Replaced ">_" with "$". Looks much better and I also updated some of the design and content on the site. Update is live.
timdaub 6y ago
Great idea! Already found some useful oneliners. Actually I do a similar thing by collecting useful commands in a git repository: https://github.com/TimDaub/commands https://github.com/TimDaub/commands
pw6hv 6y ago
Nitpick but the icon for GIT is actually that of Github. These should be used instead: https://git-scm.com/downloads/logos https://git-scm.com/downloads/logos
- pw6hv 6y ago
  The comment above referred to the URL before they changed it to command-fu. The previous URL was: https://linuxcommandlibrary.com/basic/oneliners.html https://linuxcommandlibrary.com/basic/oneliners.html
spiderfarmer 6y ago
The oneliners are very useful, but the design of this website is awful. The content deserves better.
- lgeorget 6y ago
  Yeah, I hate being that kind of guy but seriously... oneliners displayed over 5 lines because the columns are very small, commands in dark red on black...
- drran 6y ago
  Try this interface: https://www.commandlinefu.com/commands/browse https://www.commandlinefu.com/commands/browse
- skinnyasianboi 6y ago
  Author of linuxcommandlibrary.com here. Reasonable feedback. The design isn't great and can only get better from here one. I pushed some quick design updates with a new standard font, decreased the font size for the headline, slightly bigger columns and some other fixes and improvements
gpmcadam 6y ago
See also: https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes
hyper_reality 6y ago
Nice list, here are suggestions for improving a few of the commands: Generate Random Passwords >_ < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6 This produces a 6-character password which only has 35 bits of entropy. It also doesn't print a newline, causing the password to be on the same line as the next prompt. Better to use something like: >_ < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12 && echo Or the "pwgen" utility which can do this for you. Find the process that is using a certain port e.g. port 3000 >_ lsof -P | grep ':30000' This command will be extremely slow on large systems with a lot of open files. It is essentially listing every open file (the -P flag just inhibits port mappings from e.g. "port 22" to "SSH") and then grepping the output. Much better to run: >_ lsof -i :30000 Which is not only shorter, but much faster as it directly gets info about that port. Add your public SSH key to a server in one command >_ cat .ssh/id_rsa.pub | ssh hostname 'cat >> .ssh/authorized_keys' This is what the "ssh-copy-id" utility, which is part of the openssh-client package, does already. Harder, Faster, Stronger SSH clients >_ ssh -4 -C -c blowfish-cbc All three of those points are debatable with that command. Just use the defaults.
- deleted 6y ago
  [deleted]
- rovr138 6y ago
  >_ find . -empty -type d -exec rmdir {} + alternative >_ find . -empty -type d -delete
  - chasil 6y ago
    Please don't use -exec. Use -print0 and xargs -0 instead, as it's much safer, and correctly passes newlines and other problem characters. Even BSD adopted this idiom. GNU find says this very specifically: "There are unavoidable security problems surrounding the -exec action..."
    - rovr138 6y ago
      I'm pretty sure it's a bit faster too. Or for some reason I moved to it.
raptortech 6y ago
+1 for content -1 for formatting. Can we at least get a monospace font here?
- skinnyasianboi 6y ago
  Thanks for the feedback. sans-serif is the new standard font. Looks better you were right.
Foivos 6y ago
>_ cat <file> > /dev/null It mentions that this command loads the file to RAM for faster usage. I do not understand how this works. How do you access the "RAM version" of the file. Also, I thought that /dev/null was just an "abyss" you would send unwanted outputs.
- rovr138 6y ago
  Because you read the file, until the ram doesn't get purged, the file will be cached there (assuming it all fits)
- augusto-moura 6y ago
  Maybe is relying on the linux caching the file in memory? Then if you read it again is already in memory. If so I don't think it is particularly useful, given that using the file anyway already puts it into the cache for later use And yes, /dev/null is a abyss and everything written in it is discarded
- butterthebuddha 6y ago
  See https://tldp.org/LDP/sag/html/buffer-cache.html https://tldp.org/LDP/sag/html/buffer-cache.html.
- dspillett 6y ago
  You can't specifically access the cached version, but the OS will (assuming the file isn't too large) remember the blocks read from disk in the cache for a while (until the memory is needed by something else) so that next time the file is ready those blocks do not need to be read from disk. This can make a huge difference on traditional drives. /dev/null is the abyss, but the cat command will read all the blocks comprising the file from the filesystem before sending them to that abyss. You can see the effect like so: dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m3.830s user 0m0.000s sys 0m0.468s dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m0.165s user 0m0.004s sys 0m0.164s dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m0.148s user 0m0.000s sys 0m0.144s (if "a.bigish.file" has only just been created, it will likely already be in RAM, run sync; echo 3 > /proc/sys/vm/drop_caches as root or other privileged user to clear the not-currently-active cache & buffers, or chose an older file) (note though that this clears all cache machine-wide, not just cached information from your current session)
X86IpodInsame 6y ago
Wired
cestith 6y ago
I'm unsure what the "sort dotted quads" one-liner is really supposed to buy you. Yes, you can define multiple keys and all that. But an IPv4 address in dotted notation is literally indistinguishable from a multi-part semantic version number. sort -V
asicsp 6y ago
Here's some more lists (better formatted) * http://www.compciv.org/unix-tools/ http://www.compciv.org/unix-tools/ * https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes * https://linoxide.com/linux-how-to/linux-commands-brief-outline-examples/ https://linoxide.com/linux-how-to/linux-commands-brief-outli... * https://github.com/learnbyexample/Command-line-text-processing https://github.com/learnbyexample/Command-line-text-processi... --> this is my own repo on text processing commands like grep/sed/awk/sort/pr/paste/etc Bonus: * https://github.com/jlevy/the-art-of-command-line https://github.com/jlevy/the-art-of-command-line * https://stackoverflow.com/questions/68372/what-is-your-single-most-favorite-command-line-trick-using-bash https://stackoverflow.com/questions/68372/what-is-your-singl...
- nikisweeting 6y ago
  Also https://docs.monadical.com/s/system-monitoring-tools https://docs.monadical.com/s/system-monitoring-tools
tug0fwar 6y ago
> Get your external IP address > > >_ curl ip.appspot.com IMHO, entries like this are misleading for a beginner (a bad apple in the basket)
- pbhjpbhj 6y ago
  Why misleading? I use `curl icanhazip.com` pretty regularly. Are you considering security issues of echoing the content to the console, or is something else the matter?
mkovach 6y ago
There is an easy way to display re-display a lines with a time stamp. While I enjoy seeing people awk, the command is a bit terse. Instead I recommend something like: tail -f /some/file | perl -nle 'print scalar(localtime),":",$_' and it a bit easier to type IMHO.
- reacweb 6y ago
  I fully agree: each time a command in awk or sed or bash becomes complex, it is the right time to switch to perl. Perl does not have all the limitations of (awk, sed, bash) while having concise syntax.
tchelow 6y ago
Its always good to have a cheat sheet
tomkat0789 6y ago
These are neat, but is there an explanation for how/why these actually work? (Joke alert!) What sort of n00b just copies and runs random shell commands from the internet without understanding them? (End 'joke)
- pbhjpbhj 6y ago
  Perhaps https://explainshell.com/ https://explainshell.com/ does the necessary?
- jcynix 6y ago
  Who? Maybe all folks who use "curl ... | bash" or even "curl ... | sudo bash" which seems to be a trend lately?
danso 6y ago
I still primarily rely on StackOverflow for most of my shell one-liner needs, but I've found it extremely helpful to make a list/spreadsheet of the commands I repeatedly find myself having to google: https://github.com/dannguyen/bashfoo#toc https://github.com/dannguyen/bashfoo#toc
- pbhjpbhj 6y ago
  I save all my history and have a little script to grep it for commands I've used. There was a thread on here about a shell add-on that would recommend one-liners, but I can't recall it ... anyone have any ideas? Also I'd like a more robust version of my saved commands history (after 10 years or so it's getting to be like I want to make it a bit slicker), maybe backed by sqlite or something. Any suggestions?
  - BenjiWiebe 6y ago
    Do you know about ctrl-R? At the prompt in bash, it lets you search your previous commands and edit and run them right there. Combined with a large HISTSIZE it's really useful.
    - pbhjpbhj 6y ago
      Yes, thank you. Also starting to type a command and using up-arrow to scroll through (I assume) endings of that command line that are in history. That's great too. But I often don't do, say,a do-release-upgrade (I use Kubuntu but prefer command line upgrade) within the time the command stays in history.
hosteur 6y ago
This seems to be a rip off of https://www.commandlinefu.com/ https://www.commandlinefu.com/ In fact, I just checked a few commands and descriptions on this site, and they are identical in formulation of both the command and the description. Also, one of the first commands on this site is: New Maintainer for CommandLineFu >_ mail tech@commandlinefu.com Why would it even mention this other site's name here unless it was a complete copy/paste of the commands from the other site?
- asicsp 6y ago
  Oh wow, can we get the link changed to https://www.commandlinefu.com/ https://www.commandlinefu.com/ instead?
- SPBS 6y ago
  https://www.commandlinefu.com/commands/view/25015/display-information-about-the-cpu https://www.commandlinefu.com/commands/view/25015/display-in... Wow it looks like every thread is full of spam comments, really unfortunate.
  - goe1zorbey 6y ago
    SEO playing dirty. They have injected random content and a link. Most probably, they are profiting the reputation of commandlinefu.com, trying increase the google score of their sites.
- Aperocky 6y ago
  tbh both sites UI is extremely user unfriendly. I'd rather search google.
- Yajirobe 6y ago
  which one came first?
- skinnyasianboi 6y ago
  Author of linuxcommandlibrary.com here Yes I used the https://www.commandlinefu.com/site/api https://www.commandlinefu.com/site/api to get the data. I should have mentioned it on the site. And I will add in in the next update. https://linuxcommandlibrary.com/basics.html https://linuxcommandlibrary.com/basics.html has also lots of other info/tips to offer not just the one liners so it's not just a rip off of the particular website :)
gpanders 6y ago
I wrote a shell script [1] that allows me to write my own mini-man pages to capture things exactly like this. Whenever I have to do something non-trivial on the command line that I will 1) likely need to do again at some point and 2) don’t do often enough to commit it to memory, I simply create a new little note. They are viewable in the terminal just like normal man pages so the notes are trivial to read once written. It’s worked extremely well for me! [1]: https://git.sr.ht/~gpanders/ual https://git.sr.ht/~gpanders/ual
- tobib 6y ago
  Nice, this is exactly what I needed. I had my one liners in Notable to look them up but this is way more seamless AND it integrates great with Notable at the same time with the UAL folder in the Notable notes directory and a slightly more complex UAL "edit" to add the Notable metadata.
ape4 6y ago
There seems to multiple `rename` commands - messy. https://wiki.linuxquestions.org/wiki/Rename https://wiki.linuxquestions.org/wiki/Rename
- aruggirello 6y ago
  BTW: > Remove all spaces from all files in current folder should really be "from all file names".
clktmr 6y ago
It would be nice to have these available as snippets on the command line with fuzzy search.
NoSalt 6y ago
I LOVE stuff like this. Thanks!
tartoran 6y ago
These are great but, ideally one shouldn't have to leave the command line to get a cheatsheet, it would be great to get a TUI and scroll through bash snippets right from the command line. Is there such tool?
humanistbot 6y ago
I'd link to this site sorted by votes, rather than sorted by new: https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes
- skinnyasianboi 6y ago
  Author of linuxcommandlibrary.com here. Thanks! That's how it actually was in the past. Makes a huge difference. Fixed it.
mraza007 6y ago
I love the site, I was looking for something similar a while ago and I guess I found it today. As I spend most of my time in command line this website can really teach me new ways
chairmanwow1 6y ago
I think we should change the link to sort by votes all-time [1]. It's just fun to go through and see some of this stuff. The longer I use the terminal, the more of its power I come to respect. There's so many tools, so many parameters for each tool. It takes a really long time to build up muscle memory of what things you can do and remembering how to do them in that perfect situation. Recently I've been trying to take at least 20 minutes a day to try and do things the tricky way by stringing these commands together. It's fun and the productivity wins of being able to string together several of these things in a pinch is fantastic. Although it's definitely more fun than useful at this point~ [1] https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes
0x4164 6y ago
https://pastebin.com/raw/PbFCZc6K https://pastebin.com/raw/PbFCZc6K
bla3 6y ago
Does anyone have the original link this was submitted as? I looked at it earlier today and thought I should look at it again later but now it points to much less interesting commands.
- skinnyasianboi 6y ago
  There you go :) https://linuxcommandlibrary.com/basic/oneliners.html https://linuxcommandlibrary.com/basic/oneliners.html
ogre_codes 6y ago
Probably my favorite MacOS one liner (which is slightly different on Linux) is recursive search and replace) find . -name "*.tsx" -exec sed -i "" -e "s/SomeVariable/ReplacementVariable/g" {} + Use this so much with refactoring. Also... wish HN supported at least a bit of markdown.
- rovr138 6y ago
  2 spaces is a code block - https://news.ycombinator.com/formatdoc https://news.ycombinator.com/formatdoc
  - ogre_codes 6y ago
    Thanks It's like the bad-old days where every site had it's own markup though
iblaine 6y ago
My most obscure cool one liner... 1. Pointing your webserver to your current directory. Simplifies copying files to your local box. The simple python 3.x way... python -m http.server 8001 And the original way I used to do it... function sfiles() { x=`ipconfig getifaddr en0`;echo $x:8001;ruby -run -ehttpd . -p8001; } And please use this with *extreme* caution because any files you've got access to on your remote box will have no authentication when they're exposed via HTTP. My most frequently used one liner... 2. Regex searching files in directories. grep -inR <keyword> * The Silver Searcher, aka ag, is better but not natively installed so...

338 points by arkj 6y ago

Using conditional includes in your global gitconfig based on the path is a much less error prone way of having different identities for different projects. https://www.motowilliams.com/conditional-includes-for-git-config https://www.motowilliams.com/conditional-includes-for-git-co...

wruza 6y ago

>_ This part will likely confuse people who are not familiar with shell and will create a bunch of thousands "_" files worldwide. Quick explanation: >_ echo hello or equivalently: echo hello >_ when executed in a shell creates a file named "_" with contents of "hello". Author seems to use ">_" as a terminal icon, but many will copy it as part of a command. That is, if I'm not missing anything clever here. Upd: copy button doesn't copy the >_ part, so the "icon" theory seems to be correct.

0xf8 6y ago
also it’s called a shell prompt for what it’s worth.
kps 6y ago
A ‘trick’ for fancy prompts containing information is to give them the form, : all the stuff; As long as ‘all the stuff’ is parseable as shell words (which you can ensure by quoting with printf '%q' if there's doubt), then you can copy and paste entire lines. The trivial copyable prompt would be :;
- chrisweekly 6y ago
  Thank you for this!! TIL. Immediately adopting. Now wishing everyone else knew this too.
  - kps 6y ago
    I read about this long ago, possibly in the Blit era, possibly in ;login: (other order, other reasons). It's old lore, but not widely known, so I try to mention in when the subject of prompts comes up.
- Arnavion 6y ago
  Note that this isn't guaranteed to be a no-op for arbitrary "all the stuff". Specifically it won't work for commands involving pipes, or commands involving command substitution / process substitution. That is: : bar "$(foo)" : bar <(foo) : < <(foo) bar : bar | foo will all still execute `foo`
  - kps 6y ago
    That's why I mentioned quoting.
loudmax 6y ago
Agreed, including the ">_" prompt in the command line isn't really helpful. The copy icon works, it's extra unnecessary cognitive overhead. Also, ">_" is an unusual prompt, I don't know what distro ships with that by default.
- LukeShu 6y ago
  ">" is the prompt on MS-DOS, and "_" is the cursor. Somehow this has resulted in ">" or ">_" being the terminal "icon" even in unixy parts of the world; looking at the generic "utilities-terminal" icon: the default theme for Gnome 3 ("Adwaita") uses ">_" in the icon, the default theme for KDE ("Breeze") uses ">", and the runner-up ("Oxygen", which also comes bundled with KDE), also uses ">_".
  - scarmig 6y ago
    Also, the SSH app on Chromebooks.
  - marcosdumay 6y ago
    That's unfortunate, because on Linux the shells tend to use ">" for a continuation prompt, where you can not enter complete commands.
tasuki 6y ago
Yes, I wonder what benefit there is to include `>_` as the prompt. The obvious drawback is confusing some poor souls. Also it's ugly, who would want to use `>_` as their prompt?
roosgit 6y ago
It could have at least a less prominent color. And it could be added with a `::before` pseudo-element so you can't select it (just for decoration). Might be also annoying for screen readers without `aria-hidden`.
bluedino 6y ago
Am I some sort of weirdo because I don't recall seeing >_ used before as a prompt?
- prionassembly 6y ago
  _ is the blinking cursor. Prompt is just >
  - bluedino 6y ago
    But it doesn't blink.... > is kind of and odd prompt as well.
    - wruza 6y ago
      I think it is from the dos/windows world. A:\>_
      - pbhjpbhj 6y ago
        Or Acorn Electron BASIC >_ or whatever, it's a standard prompt if you're old enough!
    - nulbyte 6y ago
      That is a default in some current and old Unix systems, as well as the tcsh shell.
tomcooks 6y ago
the author should hide that "> _" by including it as a CSS :before or :after content, which by definition is not selectable.
- skinnyasianboi 6y ago
  Author of linuxcommandlibrary.com here. I did a quick fix and replaced ">_" with "$". I will dig into CSS :before during the next update. Thanks for the idea.
skinnyasianboi 6y ago
Author of linuxcommandlibrary.com here. You are 100% right. That was quite dump. I think I got the idea from the SSH icon I used in the basics page. Replaced ">_" with "$". Looks much better and I also updated some of the design and content on the site. Update is live.

timdaub 6y ago

Great idea! Already found some useful oneliners. Actually I do a similar thing by collecting useful commands in a git repository: https://github.com/TimDaub/commands https://github.com/TimDaub/commands

pw6hv 6y ago

Nitpick but the icon for GIT is actually that of Github. These should be used instead: https://git-scm.com/downloads/logos https://git-scm.com/downloads/logos

pw6hv 6y ago
The comment above referred to the URL before they changed it to command-fu. The previous URL was: https://linuxcommandlibrary.com/basic/oneliners.html https://linuxcommandlibrary.com/basic/oneliners.html

spiderfarmer 6y ago

The oneliners are very useful, but the design of this website is awful. The content deserves better.

lgeorget 6y ago
Yeah, I hate being that kind of guy but seriously... oneliners displayed over 5 lines because the columns are very small, commands in dark red on black...
drran 6y ago
Try this interface: https://www.commandlinefu.com/commands/browse https://www.commandlinefu.com/commands/browse
skinnyasianboi 6y ago
Author of linuxcommandlibrary.com here. Reasonable feedback. The design isn't great and can only get better from here one. I pushed some quick design updates with a new standard font, decreased the font size for the headline, slightly bigger columns and some other fixes and improvements

gpmcadam 6y ago

See also: https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes

hyper_reality 6y ago

Nice list, here are suggestions for improving a few of the commands: Generate Random Passwords >_ < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6 This produces a 6-character password which only has 35 bits of entropy. It also doesn't print a newline, causing the password to be on the same line as the next prompt. Better to use something like: >_ < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c12 && echo Or the "pwgen" utility which can do this for you. Find the process that is using a certain port e.g. port 3000 >_ lsof -P | grep ':30000' This command will be extremely slow on large systems with a lot of open files. It is essentially listing every open file (the -P flag just inhibits port mappings from e.g. "port 22" to "SSH") and then grepping the output. Much better to run: >_ lsof -i :30000 Which is not only shorter, but much faster as it directly gets info about that port. Add your public SSH key to a server in one command >_ cat .ssh/id_rsa.pub | ssh hostname 'cat >> .ssh/authorized_keys' This is what the "ssh-copy-id" utility, which is part of the openssh-client package, does already. Harder, Faster, Stronger SSH clients >_ ssh -4 -C -c blowfish-cbc All three of those points are debatable with that command. Just use the defaults.

deleted 6y ago
[deleted]
rovr138 6y ago
>_ find . -empty -type d -exec rmdir {} + alternative >_ find . -empty -type d -delete
- chasil 6y ago
  Please don't use -exec. Use -print0 and xargs -0 instead, as it's much safer, and correctly passes newlines and other problem characters. Even BSD adopted this idiom. GNU find says this very specifically: "There are unavoidable security problems surrounding the -exec action..."
  - rovr138 6y ago
    I'm pretty sure it's a bit faster too. Or for some reason I moved to it.

raptortech 6y ago

+1 for content -1 for formatting. Can we at least get a monospace font here?

skinnyasianboi 6y ago
Thanks for the feedback. sans-serif is the new standard font. Looks better you were right.

Foivos 6y ago

>_ cat <file> > /dev/null It mentions that this command loads the file to RAM for faster usage. I do not understand how this works. How do you access the "RAM version" of the file. Also, I thought that /dev/null was just an "abyss" you would send unwanted outputs.

rovr138 6y ago
Because you read the file, until the ram doesn't get purged, the file will be cached there (assuming it all fits)
augusto-moura 6y ago
Maybe is relying on the linux caching the file in memory? Then if you read it again is already in memory. If so I don't think it is particularly useful, given that using the file anyway already puts it into the cache for later use And yes, /dev/null is a abyss and everything written in it is discarded
butterthebuddha 6y ago
See https://tldp.org/LDP/sag/html/buffer-cache.html https://tldp.org/LDP/sag/html/buffer-cache.html.
dspillett 6y ago
You can't specifically access the cached version, but the OS will (assuming the file isn't too large) remember the blocks read from disk in the cache for a while (until the memory is needed by something else) so that next time the file is ready those blocks do not need to be read from disk. This can make a huge difference on traditional drives. /dev/null is the abyss, but the cat command will read all the blocks comprising the file from the filesystem before sending them to that abyss. You can see the effect like so: dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m3.830s user 0m0.000s sys 0m0.468s dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m0.165s user 0m0.004s sys 0m0.164s dspillett@swann2:/tmp$ time cat a.bigish.file > /dev/null real 0m0.148s user 0m0.000s sys 0m0.144s (if "a.bigish.file" has only just been created, it will likely already be in RAM, run sync; echo 3 > /proc/sys/vm/drop_caches as root or other privileged user to clear the not-currently-active cache & buffers, or chose an older file) (note though that this clears all cache machine-wide, not just cached information from your current session)

X86IpodInsame 6y ago

Wired

cestith 6y ago

I'm unsure what the "sort dotted quads" one-liner is really supposed to buy you. Yes, you can define multiple keys and all that. But an IPv4 address in dotted notation is literally indistinguishable from a multi-part semantic version number. sort -V

asicsp 6y ago

Here's some more lists (better formatted) * http://www.compciv.org/unix-tools/ http://www.compciv.org/unix-tools/ * https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes * https://linoxide.com/linux-how-to/linux-commands-brief-outline-examples/ https://linoxide.com/linux-how-to/linux-commands-brief-outli... * https://github.com/learnbyexample/Command-line-text-processing https://github.com/learnbyexample/Command-line-text-processi... --> this is my own repo on text processing commands like grep/sed/awk/sort/pr/paste/etc Bonus: * https://github.com/jlevy/the-art-of-command-line https://github.com/jlevy/the-art-of-command-line * https://stackoverflow.com/questions/68372/what-is-your-single-most-favorite-command-line-trick-using-bash https://stackoverflow.com/questions/68372/what-is-your-singl...

nikisweeting 6y ago
Also https://docs.monadical.com/s/system-monitoring-tools https://docs.monadical.com/s/system-monitoring-tools

tug0fwar 6y ago

> Get your external IP address > > >_ curl ip.appspot.com IMHO, entries like this are misleading for a beginner (a bad apple in the basket)

pbhjpbhj 6y ago
Why misleading? I use `curl icanhazip.com` pretty regularly. Are you considering security issues of echoing the content to the console, or is something else the matter?

mkovach 6y ago

There is an easy way to display re-display a lines with a time stamp. While I enjoy seeing people awk, the command is a bit terse. Instead I recommend something like: tail -f /some/file | perl -nle 'print scalar(localtime),":",$_' and it a bit easier to type IMHO.

reacweb 6y ago
I fully agree: each time a command in awk or sed or bash becomes complex, it is the right time to switch to perl. Perl does not have all the limitations of (awk, sed, bash) while having concise syntax.

tchelow 6y ago

Its always good to have a cheat sheet

tomkat0789 6y ago

These are neat, but is there an explanation for how/why these actually work? (Joke alert!) What sort of n00b just copies and runs random shell commands from the internet without understanding them? (End 'joke)

pbhjpbhj 6y ago
Perhaps https://explainshell.com/ https://explainshell.com/ does the necessary?
jcynix 6y ago
Who? Maybe all folks who use "curl ... | bash" or even "curl ... | sudo bash" which seems to be a trend lately?

danso 6y ago

I still primarily rely on StackOverflow for most of my shell one-liner needs, but I've found it extremely helpful to make a list/spreadsheet of the commands I repeatedly find myself having to google: https://github.com/dannguyen/bashfoo#toc https://github.com/dannguyen/bashfoo#toc

pbhjpbhj 6y ago
I save all my history and have a little script to grep it for commands I've used. There was a thread on here about a shell add-on that would recommend one-liners, but I can't recall it ... anyone have any ideas? Also I'd like a more robust version of my saved commands history (after 10 years or so it's getting to be like I want to make it a bit slicker), maybe backed by sqlite or something. Any suggestions?
- BenjiWiebe 6y ago
  Do you know about ctrl-R? At the prompt in bash, it lets you search your previous commands and edit and run them right there. Combined with a large HISTSIZE it's really useful.
  - pbhjpbhj 6y ago
    Yes, thank you. Also starting to type a command and using up-arrow to scroll through (I assume) endings of that command line that are in history. That's great too. But I often don't do, say,a do-release-upgrade (I use Kubuntu but prefer command line upgrade) within the time the command stays in history.

hosteur 6y ago

This seems to be a rip off of https://www.commandlinefu.com/ https://www.commandlinefu.com/ In fact, I just checked a few commands and descriptions on this site, and they are identical in formulation of both the command and the description. Also, one of the first commands on this site is: New Maintainer for CommandLineFu >_ mail tech@commandlinefu.com Why would it even mention this other site's name here unless it was a complete copy/paste of the commands from the other site?

asicsp 6y ago
Oh wow, can we get the link changed to https://www.commandlinefu.com/ https://www.commandlinefu.com/ instead?
SPBS 6y ago
https://www.commandlinefu.com/commands/view/25015/display-information-about-the-cpu https://www.commandlinefu.com/commands/view/25015/display-in... Wow it looks like every thread is full of spam comments, really unfortunate.
- goe1zorbey 6y ago
  SEO playing dirty. They have injected random content and a link. Most probably, they are profiting the reputation of commandlinefu.com, trying increase the google score of their sites.
Aperocky 6y ago
tbh both sites UI is extremely user unfriendly. I'd rather search google.
Yajirobe 6y ago
which one came first?
skinnyasianboi 6y ago
Author of linuxcommandlibrary.com here Yes I used the https://www.commandlinefu.com/site/api https://www.commandlinefu.com/site/api to get the data. I should have mentioned it on the site. And I will add in in the next update. https://linuxcommandlibrary.com/basics.html https://linuxcommandlibrary.com/basics.html has also lots of other info/tips to offer not just the one liners so it's not just a rip off of the particular website :)

gpanders 6y ago

I wrote a shell script [1] that allows me to write my own mini-man pages to capture things exactly like this. Whenever I have to do something non-trivial on the command line that I will 1) likely need to do again at some point and 2) don’t do often enough to commit it to memory, I simply create a new little note. They are viewable in the terminal just like normal man pages so the notes are trivial to read once written. It’s worked extremely well for me! [1]: https://git.sr.ht/~gpanders/ual https://git.sr.ht/~gpanders/ual

tobib 6y ago
Nice, this is exactly what I needed. I had my one liners in Notable to look them up but this is way more seamless AND it integrates great with Notable at the same time with the UAL folder in the Notable notes directory and a slightly more complex UAL "edit" to add the Notable metadata.

ape4 6y ago

There seems to multiple `rename` commands - messy. https://wiki.linuxquestions.org/wiki/Rename https://wiki.linuxquestions.org/wiki/Rename

aruggirello 6y ago
BTW: > Remove all spaces from all files in current folder should really be "from all file names".

clktmr 6y ago

It would be nice to have these available as snippets on the command line with fuzzy search.

NoSalt 6y ago

I LOVE stuff like this. Thanks!

tartoran 6y ago

These are great but, ideally one shouldn't have to leave the command line to get a cheatsheet, it would be great to get a TUI and scroll through bash snippets right from the command line. Is there such tool?

humanistbot 6y ago

I'd link to this site sorted by votes, rather than sorted by new: https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes

skinnyasianboi 6y ago
Author of linuxcommandlibrary.com here. Thanks! That's how it actually was in the past. Makes a huge difference. Fixed it.

mraza007 6y ago

I love the site, I was looking for something similar a while ago and I guess I found it today. As I spend most of my time in command line this website can really teach me new ways

chairmanwow1 6y ago

I think we should change the link to sort by votes all-time [1]. It's just fun to go through and see some of this stuff. The longer I use the terminal, the more of its power I come to respect. There's so many tools, so many parameters for each tool. It takes a really long time to build up muscle memory of what things you can do and remembering how to do them in that perfect situation. Recently I've been trying to take at least 20 minutes a day to try and do things the tricky way by stringing these commands together. It's fun and the productivity wins of being able to string together several of these things in a pinch is fantastic. Although it's definitely more fun than useful at this point~ [1] https://www.commandlinefu.com/commands/browse/sort-by-votes https://www.commandlinefu.com/commands/browse/sort-by-votes

0x4164 6y ago

https://pastebin.com/raw/PbFCZc6K https://pastebin.com/raw/PbFCZc6K

bla3 6y ago

Does anyone have the original link this was submitted as? I looked at it earlier today and thought I should look at it again later but now it points to much less interesting commands.

skinnyasianboi 6y ago
There you go :) https://linuxcommandlibrary.com/basic/oneliners.html https://linuxcommandlibrary.com/basic/oneliners.html

ogre_codes 6y ago

Probably my favorite MacOS one liner (which is slightly different on Linux) is recursive search and replace) find . -name "*.tsx" -exec sed -i "" -e "s/SomeVariable/ReplacementVariable/g" {} + Use this so much with refactoring. Also... wish HN supported at least a bit of markdown.

rovr138 6y ago
2 spaces is a code block - https://news.ycombinator.com/formatdoc https://news.ycombinator.com/formatdoc
- ogre_codes 6y ago
  Thanks It's like the bad-old days where every site had it's own markup though

iblaine 6y ago

My most obscure cool one liner... 1. Pointing your webserver to your current directory. Simplifies copying files to your local box. The simple python 3.x way... python -m http.server 8001 And the original way I used to do it... function sfiles() { x=`ipconfig getifaddr en0`;echo $x:8001;ruby -run -ehttpd . -p8001; } And please use this with *extreme* caution because any files you've got access to on your remote box will have no authentication when they're exposed via HTTP. My most frequently used one liner... 2. Regex searching files in directories. grep -inR <keyword> * The Silver Searcher, aka ag, is better but not natively installed so...