I’ve been setting up a new Proxmox server and messing around with VMs, and wanted to know what kind of useful commands I’m missing out on. Bonus points for a little explainer.

Journalctl | grep -C 10 'foo' was useful for me when I needed to troubleshoot some fstab mount fuckery on boot. It pipes Journalctl (boot logs) into grep to find ‘foo’, and prints 10 lines before and after each instance of ‘foo’.

  • InFerNo@lemmy.ml
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    1 day ago

    I use $_ a lot, it allows you to use the last parameter of the previous command in your current command

    mkdir something && cd $_

    nano file
    chmod +x $_

    As a simple example.

    If you want to create nested folders, you can do it in one go by adding -p to mkdir

    mkdir -p bunch/of/nested/folders

    Good explanation here:
    https://koenwoortman.com/bash-mkdir-multiple-subdirectories/q

    Sometimes starting a service takes a while and you’re sitting there waiting for the terminal to be available again. Just add --no-block to systemctl and it will do it on the background without keeping the terminal occupied.

    systemctl start --no-block myservice

      • wheezy@lemmy.ml
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        1 day ago

        I have my .bashrc print useful commands with a short explanation. This way I see them regularly when I start a new session. Once I use a command enough that I have it as part of my toolkit I remove it from the print.

        • pssk@lemmy.ml
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          20 hours ago

          You can use M-. instead of $_ to insert last param of last command. You can also access older commands’ param by repeated M-. just like you would do for inserting past commands with up arrow or C-p

    • Will@lemmy.ml
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      20 hours ago

      For interactive editing, the keybind alt+. inserts the last argument from the previous command. Using this instead of $_ has the potential to make your shell history a little more explicit. (vim $_ isn’t as likely to work a few commands later, but vim actual_file.sh might)

  • utopiah@lemmy.ml
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    1 day ago
    fabien@debian2080ti:~$ history  | sed 's/ ..... //' | sort | uniq -c | sort -n | tail
    # with parameters
         13 cd Prototypes/
         14 adb disconnect; cd ~/Downloads/Shows/ ; adb connect videoprojector ;
         14 cd ..
         21 s # alias s='ssh shell -t "screen -raAD"'
         36 node .
         36 ./todo 
         42 vi index.js 
         42 vi todo # which I use as metadata or starting script in ~/Prototypes
         44 ls
        105 lr # alias lr="ls -lrth"
    fabien@debian2080ti:~$ history  | sed 's/ ..... //' | sed 's/ .*//' | sort | uniq -c | sort -n | tail
    # without parameters
         35 rm
         36 node
         36 ./todo
         39 git
         39 mv
         70 ls
         71 adb
         96 cd
        110 lr
        118 vi
    
  • Geodes_n_Gems@lemmy.ml
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    2 days ago

    Running Wine is the command I’ve used the most probs, you can tell I haven’t touched the thing in months.

  • harsh3466@lemmy.ml
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    1 day ago
    find /path/to/starting/dir -type f -regextype egrep -regex 'some[[:space:]]*regex[[:space:]]*(goes|here)' -exec mv {} /path/to/new/directory/ \;
    

    I routinely have to find a bunch of files that match a particular pattern and then do something with those files, and as a result, find with -exec is one of my top commands.

    If you’re someone who doesn’t know wtf that above command does, here’s a breakdown piece by piece:

    • find - cli tool to find files based on lots of different parameters
    • /path/to/starting/dir - the directory at which find will start looking for files recursively moving down the file tree
    • -type f - specifies I only want find to find files.
    • -regextype egrep - In this example I’m using regex to pattern match filenames, and this tells find what flavor of regex to use
    • -regex 'regex.here' - The regex to be used to pattern match against the filenames
    • -exec - exec is a way to redirect output in bash and use that output as a parameter in the subsequent command.
    • mv {} /path/to/new/directory/ - mv is just an example, you can use almost any command here. The important bit is {}, which is the placeholder for the parameter coming from find, in this case, a full file path. So this would read when expanded, mv /full/path/of/file/that/matches/the/regex.file /path/to/new/directory/
    • \; - This terminates the command. The semi-colon is the actual termination, but it must be escaped so that the current shell doesn’t see it and try to use it as a command separator.
  • mr_right@lemmy.dbzer0.com
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    24 hours ago

    i do not know if this counts as a command but you might want to check Atuin, what it does is help you find, manage and edit the commands you used in your shell history saves you a lot of time

  • Lettuce eat lettuce@lemmy.ml
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    1 day ago

    The watch command is very useful, for those who don’t know, it starts an automated loop with a default of two seconds and executes whatever commands you place after it.

    It allows you to actively monitor systems without having to manually re-run your command.

    So for instance, if you wanted to see all storage block devices and monitor what a new storage device shows up as when you plug it in, you could do:

    watch lsblk
    

    And see in real time the drive mount. Technically not “real time” because the default refresh is 2 seconds, but you can specify shorter or longer intervals.

    Obviously my example is kind of silly, but you can combine this with other commands or even whole bash scripts to do some cool stuff.

    • Breadhax0r@lemmy.world
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      22 hours ago

      Ooooh cool, I think this explains how they have our raid monitor set up at work! I keep forgetting to poke through the script

      • Lettuce eat lettuce@lemmy.ml
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        17 hours ago

        Yeah, it’s a neat little tool. I used it recently at my work. We had a big list of endpoints that we needed to make sure were powered down each night for a week during a patching window.

        A sysadmin on my team wrote a script that pinged all of the endpoints in the list and returned only the ones that still were getting a response, that way we could see how many were still powered on after a certain time. But he was just manually running the script every few minutes in his terminal.

        I suggested using the watch command to execute the script, and then piping the output into the sort command so the endpoints were nicely alphabetical. Worked like a charm!

    • bigredgiraffe@lemmy.world
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      1 day ago

      To add to this one, it also supports more than just the previous command (which is what !! means), you can do like sudo !453 to run command 453 from your history, also supports relative like !-5. You can also use without sudo if you want which is handy to do things like !ls for the last ls command etc. Okay one more, you can add :p to the end to print the command before running it just in case like !systemctl:p which can be handy!

    • mel ♀@jlai.lu
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      2 days ago

      with zsh, you can use it, and then press space to have the !! replaced by the previous command to be able to edit it :)

      • smeg@feddit.uk
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        17 hours ago

        You can do this on bash too if you add bind Space: magic-space to your bashrc/profile

    • wheezy@lemmy.ml
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      1 day ago

      I forget where I got it. But mine will do this if I double tap ESC after I sent the command without sudo. Very useful.

      I should probably figure out what it was I added to do this.

      Doesn’t issue the command. Have to hit enter. Useful to verify it’s the right command first.

      With the way bash history can work Id be worried about running sudo rm -rf ./* by mistake.

    • hades@feddit.uk
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      2 days ago

      Also if you make a typo you can quickly fix it with ^, e.g.

      ls /var/logs/apache

      ^logs^log

        • ystael@beehaw.org
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          9 hours ago

          I usually spell this as !!:gs/foo/bar/ (in bash). Is there a functional difference?

          ! command history can also take line and word selectors. I type something like !-2:2 surprisingly often.

  • TechnoCat@piefed.social
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    2 days ago

    https://blog.sanctum.geek.nz/series/unix-as-ide/

    # list all recursive files sorted by size  
    $ fd -tf "" -x du -h | sort -h  
    8.0K      ./asdfrc  
     20K      ./nvim/lua/lush_theme/bleak.lua  
     32K      ./alacritty.yml  
    
    # find files by extension  
    $ fd -e lua  
    nvim/colors/bleak.lua  
    nvim/init.lua  
    nvim/lua/config/autocmds.lua  
    
    # list found files in tree view  
    $ fd -e lua | tree --fromfile  
    .  
    └── nvim  
        ├── colors  
        │   └── bleak.lua  
        ├── init.lua  
    
    # Run "npm test" when a file changes in the src or test directories  
    $ fd src test | entr -- npm test  
    
    # find out how often you use each command  
    history | cut -d " " -f 1 | sort | uniq -c | sort -n | tail -n 10  
      80 rm  
      81 lsd  
     107 asdf  
     136 npx  
     161 find  
     176 fd  
     182 cd  
     185 rg  
     247 brew  
     250 nb  
     465 npm  
     867 git  
    
  • qjkxbmwvz@startrek.website
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    2 days ago

    nc is useful. For example: if you have a disk image downloaded on computer A but want to write it to an SD card on computer B, you can run something like

    user@B: nc -l 1234 | pv > /dev/$sdcard

    And

    user@A: nc B.local 1234 < /path/to/image.img

    (I may have syntax messed up–also don’t transfer sensitive information this way!)

    Similarly, no need to store a compressed file if you’re going to uncompress it as soon as you download it—just pipe wget or curl to tar or xz or whatever.

    I once burnt a CD of a Linux ISO by wgeting directly to cdrecord. It was actually kinda useful because it was on a laptop that was running out of HD space. Luckily the University Internet was fast and the CD was successfully burnt :)

  • Valmond@lemmy.dbzer0.com
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    1 day ago

    I’ll go with a simple one here:

    CTRL+SHIFT C/V for copy paste.

    Or if it has to be terminal;

    kill

    😊

  • Auster@thebrainbin.org
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    2 days ago

    (Fixed the bolding issue)

    From a file I keep since I started using Linux near 5 years ago:

    Display the RAM usage:
    watch -n 5 free -m
    Useful if you open way too much stuff and/or you’re running on budget processing power, and don’t want your computer freezing from 3 hours.
    Also useful if you use KDE’s Konsole integrated into the Dolphin file manager and you must for some reason not close the Dolphin window. You’d just need to open Dolphin’s integrated Konsole (F4), run the command and without closing it, press F4 again to hide the Konsole.

    Terminal-based file browser that sorts by total size:
    ncdu
    why is the cache folder 50 GB big?

    Mass-check MD5 hashes for all files in the path, including subfolders:
    find -type f \( -not -name "md5sum.txt" \) -exec md5sum '{}' \; > md5sum.txt
    Change md5sum (and optionally the output file’s name) for your favorite/needed hash calculator command.

    For mounting ISOs and similar formats:
    sudo mount -o loop path/to/iso/file/YOUR_ISO_FILE.ISO /mnt/iso

    And unmounting the file:
    sudo umount /mnt/iso
    Beware there’s no N in the umount command

    For creating an ISO from a mounted disc:
    dd if=/dev/cdrom of=image_name.iso

    And for a folder and its files and subfolders:
    mkisofs -o /path/to/output/disc.iso /path/from/input/folder

    Compress and split files:
    7z -v100m a output_base_file.7z input_file_or_folder

    Changes the capslock key into shiftlock on Linux Mint (not tested in other distros):
    setxkbmap -option caps:shiftlock
    Was useful when the shift key from a previous computer broke and I didn’t have a spare keyboard.

    If you want to run Japanese programs on Wine, you can use:
    LC_ALL=ja_JP wine /path/to/the/executable.exe
    There are other options but this is one that worked the better for me so I kinda forgor to take note of them.

    List all files in a given path and its subfolders:
    find path_to_check -type f
    Tip: add > output.txt or >> output.txt if you’d rather have the list in a TXT file.

    Running a program in Wine in a virtual desktop:
    wine explorer /desktop=session_name,screen_size /path/to/the/executable.exe

    E.g.:
    wine explorer /desktop=MyDesktop,1920x1080 Game.exe

    Useful if you don’t want to use the whole screen, there are integration issues between Linux, Wine and the program, or the program itself has issues when alt-tabbing or similar (looking at you, 2000’s Windows games)

    Download package installers from with all their dependencies:
    apt download package_name
    Asks for sudo password even when not running as sudo. Downloaded files come with normal user permissions thankfully. Also comes with an installation script but if you want to run it offline, iirc you need to change apt install in the script for dpkg -i.

    If you use a program you’d rather not connect to the internet but without killing the whole system’s connection, try:
    firejail --net=none the_command_you_want_to_run

    Or if you want to run an appimage:
    firejail --net=none --appimage the_command_you_want_to_run

    If you want to make aliases (similar to commands from Windows’ PATH) and your system uses bash, edit the file $HOME/.bashrc (e.g. with Nano) and make the system use the updated file by either logging out and in, or running . ~/.bashrc

    Python/Pip have some nifty tools, like Cutlet (outputs Japanese text as Romaji), gogrepoc (for downloading stuff from your account using GOG’s API), itch-dl (same as gogrepoc but for Itch.io), etc. If you lack the coding skills and doesn’t mind using LLMs, you could even ask one to make some simpler Python scripts (key word though: simpler).

    If you want to run a video whose codec isn’t supported by your system (e.g. Raspberrian which only supports H.264, up to 1080p):
    ffmpeg -i input_video.mkv -map 0 -c:v libx264 -preset medium -crf 23 -vf scale=1920:1080 -c:a copy -c:s copy output_video.mkv

  • roran@sh.itjust.works
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    1 day ago
    cd `pwd`
    

    for when you want to stay in a dìr that gets deleted and recreated.

    cat /proc/foo/exe > program
    cat /proc/foo/fd/bar > file
    

    to undelete still-running programs and files still opened in running programs

  • Ŝan • 𐑖ƨɤ@piefed.zip
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    2 days ago

    ripgrep has mostly replaced grep for me, and I am extremely conservative about replacing core POSIX utilities - muscle memory is critical. I also tend to use fd, mainly because of its forking -x, but its advantages over find are less stark þan rg’s improvements over grep.

    nnn is really handy; I use it for everything but the most trivial renames, copies, and moves - anyþing involving more þan one file. It’s especially handy when moving files between servers because of þe built-in remote mounting.

    • marighost@piefed.socialOP
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      2 days ago

      Would you recommend nnn for transfering ~5Tb of media between two local servers? Seems like a weird question but it’s something I’ll have to do soon.

        • marighost@piefed.socialOP
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          2 days ago

          I could very easily, I’ve just only use rsync a handful of times for one-off files or small directories. Thinking of using it for several Tbs scares me 😅

          • ScientifficDoggo@lemmy.zip
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            1 day ago

            I’m sure it’ll be fine, I’m no expert but i use it it sync/clone my music storage with my music player. There’s thousands of songs, lyrics, and album art getting synced and backed up regularly in my case.

            Worst thing that happened to me happened when I was new to the tool and accidentally overwrote my source directory (luckily I had backups)

          • ranzispa@mander.xyz
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            1 day ago

            When transfering large amounts of data I’d most definitely advise using rsync. Something fails, connection falls and everything is okay as it’ll pick up where it left off.

      • Ŝan • 𐑖ƨɤ@piefed.zip
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        1 day ago

        No. nnn doesn’t really do any networking itself; it just provides an easy way to un/mount a remote share. nnn is just a TUI file manager.

        For transfering 5TB of media, I’d acquire a 5TB USB 3.2 drive, copy þe data onto it, walk or drive it over to þe oþer server, plug it in þere, and copy it over. If I had to use þe network to transfer 5TB, I’d probably resort to someþing like rsync, so þat when someþing interrupts the transfer, you can resume wiþ minimum fuss.

    • emb@lemmy.world
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      2 days ago

      rg and fd have been so much easier to use than the classics to me. Great replacements!

      bat is another one that I think can be worth switching to, though not as essential.